Both zone maps are flawed and are meant to be used as a baseline for your general area. The updated map takes the urban heat island effect into account as well as the recorded warming trend over the last 30.

Its also hard to take smaller microclimates into account as well. There is a narrow band of zone 4 and 5 near the lake here, whereas you go 20 miles away its zone 3. IT would also depend on where the temp data is taken. Here it is 18km away from the lake so its just on the edge of the moderating effect.

The best thing is to use the zone maps as a guide, and install a few thermometers around your yard so you can see proper temps and how buildings/trees affect certain areas.

It also doesnt take into account us using protection as well as snowpack/leaf litter which effects a plants survival.

Beng, where can I get a min/max thermometer? Is it something easily found at the big box stores, or something more complicated to find? Canadianplant, I've had people mention microclimates before to me, that is good for small plants especially, unless of course it's a large body of water or the heat island effect of a big city. I still want to grow things that like it warmer in winter than it stays here, but I have had good luck with some plants that were supposed to be zone 7, but the growers had hinted on them possibly being back-crossed with a hardier Variety of their species and I think I hit the jackpot and have what I have been doggedly searching for, (a zone 6 hardy regular sized Live oak tree) but spring will prove if I am right or not for sure, as of today it still looks okay.. So if my zone isn't warmer, I'll be happy if the tree can adapt due to it's genetics. The Palms can be covered in the worst freezes. I can take em or leave them I guess. I just have this love of Live oak trees, I have a couple doing fine but they are slow growing and those closer related to the full sized Q. Virginiana are my quary. I have 2 or 3 that I am happy to say, have survived this winter, so far. Although not below zero, it has been a tough winter compared to at least the last few. We have had many days of teens and low 20's. One is in a pot but close to the house.

"Beng, where can I get a min/max thermometer?"

Heard of google?
go to http://www.google.com/shopping

enter
"min/max thermometer"
don't forget to press the submit icon next to the text box!

Depends on what you want to do, but there are a whole variety of home weather stations out there. I put that in the link below. Usually (but not always) you get more bang for your buck, including accuracy. Of course, a weather station won't be reliable if you don't site it properly, which means out in the open, away from trees and buildings (at least, as much as is possible for your property). I have two stations, one at my parents' home in New Jersey and one here in Nevada.

Here's the one in New Jersey.

Here is a link that might be useful: Home weather stations google search

The anemometer is located up on a conveniently located utility support pole ;) See link below for the data from the electronic portion of the station.

Here is a link that might be useful: Ewing NJ weather station data

And here's the one I have here in Nevada. Again, see link at bottom for the data from the electronic portion.

Here is a link that might be useful: Elko NV weather station data

I sure would like to have that first setup there, famartin. And the rain that falls from the sky.

The set-up in NV and NJ is very high tech if you can access the info online. Can I get a min/max thermometer that is self contained and easier or is this what you have too Beng? And davidrt28 I wanted a reply from someone who has and recommended one of these thermometers to me. I hate google and don't go on the shopping links because the results you get are often CRAP. Many posters on here can Google for the answer to their question, but real people can sometimes help better than a stupid search engine, take your attitude and stuff it up your pattutty.

Regardless of the reasoning, the last 30 years have on a general warming trend for most of NA. The thing is when people hear that, they dont understand that the swings will still go both ways. Just because we are in a warming trend, does not mean Arizona wont get snow, if anything the variability that is now in the atmosphere will make it more likely to happen.

The other thing you have to take into concideration when looking at your areas climate data, is where it taken. Here its taken at the airport which is roughly 20km from the lake. The south facing hills that surround the city, coupled with the lake creates a moderating effect that can leave winter temps around 5C warmer than near the airport. Ive tested this and its true.

The zone maps dont take into account smaller micro climates, rainfall, and late frosts. The only way to be sure is to set up multiple thermometers and use plants that have reliable information (indicator plants)

I definitely think the ranges for WI are too widespead. I'm 10 miles outside the 5b zone so I'm very comfortable using zone 5 plants. Sometimes I'll try a borderline 5/6 plant. Based on temperature alone my area averages 3-5 degrees colder than my friends closer to the lake.

What I don't understand is that my friends 100 miles north are zone 5a yet and based on temperature alone average 10-13 degrees colder.

I guess thats where you'd consider the low and high range between zones. However someone north of me might focus on the higher range of lows thinking they can stretch it but in reality they're at the lower range of lows. Just another factor to consider. At the end of the day I think it takes quite abit of observation of your specific weather trends (even in your own yard), looking at some historical data then the plants themselves.

In the last 7 years I've only seen the upper end of lows (-15) hit a couple times. Last year it never dropped below zero. This year hit -8 for a low (so far). Its bound to happen (every 20 years or so) but I'm hoping that -25 never hits during my gardening tenure. Mainly as it means there will likely be a stretch.

I still find it hard to beleive that there were any - 0's each time those years were listed above in this thread, but if it is listed as happening somewhere about 5-6 miles from me, I can't argue with a reputable source of data. I am not going to purchase a expensive set-up, but will see if I can find something that can store info short term, to be checked daily, and put it away from the house but not too far as to not be able to check it in a lot of snow.

12 to 18 inches snow forecast for my area on Wednesday. March indeed.

Poaky, just get a min/max thermometer & a simple stick-in-the-ground (or mount if you want) rain-gauge. I don't check mine every day, just after a rain event or temperature extreme. I used to record daily (for yrs), but it was too much of a bother.

Sure would be nice to have an affordable automated option that connects with your wifi and updates to an online server for daily temp/precip records. You could then log in from anywhere to check your records. I would shell out a couple Benjamens for this setup and I would think it shouldn't be that difficult to manufacture.

Beng, I think Poaky was hoping you could do something like point him in the direction of a specific product you'd recommend, like a link to it on Amazon or something.

I can't really help since I have the "high tech, expensive" setup and never tried one of the lower tech ones.

There are cheaper systems out there than the two I have. LaCrosse and Oregon Scientific manufacture them. The one I have is made by Davis Instruments and they are a pretty penny (but very reliable with virtually no maintenance).

jon, I'll sign up for that too! Then I have my own history from my yard.

Lets go in on this and patent it.

The problem I've run into is that the batteries run into trouble at temperatures below about zero. Since that is where I start being fascinated by winter temperatures, it makes the cheaper sensors useless.

Places like Agway sell min/max thermometers. I've got two of them. One lives on the back deck, the other in the garage. Since I overwinter a fair number of plants in the garage, it's good to know what sorts of temperatures they are exposed to.

The Davis one I have here in Nevada was down to -16 a couple times this winter with daytime highs in the single digits, it performed pretty well. Only a degree or so difference from the nearby airport station.

Removed to protect trade secrets ;)

This post was edited by j0nd03 on Thu, Mar 7, 13 at 10:02

I'm sure what is high tech to me is not high tech to some on here. Luckily there is an Agway not far from me. I can check there and on the internet. They are probably easy to find.

8" of wet snow here yesterday, weighing down branches, but fortunately got blown off/melted after just a few hrs. Far more snow just to the south in the WV panhandle.

I was amazed to find a weather center unit at WAL-Mart for approx. $100.00. I guess that is why lots of folks have them. I am not concerned with rainfall much. We get what I would imagine is normal rainfall or there would be a ruckus about it . So I will get it next payday and can keep track of my winter lows in my yard.

Sorta cross-posting this, but only to a thread not a new thread, because the Midatlantic forum is rather moribund. As to the original reason for this post: as several other people said, every area of every state north of NC has been well below zero. Some places are just barely below like Cape May NJ at -2F. Every point in VA has been below 0F...in 1985 my relatives who live right on the beach said the temp was below 0F and oleanders were all killed to the ground. The first state with a relatively large area never to go below 0F is NC at Cape Hatteras, NC, that has only been to 6F. To evaluate "ever", you have to have have a site for which 1899 data is available.

Trying to get a feel for the pattern of cold winters in the eastern US for the past 100 or so years.
Certainly three periods stand out: the legendary winter of 1899 still holds the crown as the single worse regional cold spell in modern history: downtown DC's all time record low of -15F, Baltimore's of -7F, and Florida's only subzero record at -2F. In terms of overall periods, the two leaders are the early 1930s, and 1977-1985, ending with the locally famous Reagan inauguration freeze, one of the last times central DC went below 0F. In 1932, College Park, Maryland hit an astonishing -26F! Much closer to DC than Dulles airport's -18F all time record low in 1984. Baltimore hit -7F again in 1934.
Other periods I can find: the winter of 1961 has records for several areas and dates. 1994 and to some degree 1996. 1918, 1905, and 1957 were cold, too. Generally speaking, you hardly see any cold records for the 20s, 40s, and 60s other than 61.

However here in the upper Bay region of Maryland, an elderly neighbor who moved here in 1960, tells me winters used to much colder. That people used to skate on a local pond that I haven't seen anywhere close to fully & safely frozen at all in the past 8 years. Also her recollection doesn't exactly jibe with what I know about the history of camellias at the National Arboretum. Many plants planted in the 50s and 60s died in the winters of the late 70s. So were winters before the 1990s colder on average, but, other than the big freezes of the late 70s and mid 80s, less prone to severe sub 0F freezing?

http://www.sercc.com/climateinfo/historical/historical.html

Once you click on a location, the "Daily Summary Stats" are particularly useful, in additional to the general temperature summary page. Alas there is no similar site for the northeastern US that I am aware of. There is one for the west, appropriately called the western regional climate center.

Here is a link that might be useful: http://www.sercc.com/climateinfo/historical/historical.html

This post was edited by davidrt28 on Wed, Nov 13, 13 at 17:36

Interesting stuff, David.

Perhaps the "cold winters" your elderly neighbor remembers WERE the late 70s...

On casual observation, it does seem that although '57 was cold, the 30s through the 50s, in general, were warmer overall than the 60s through the 80s. The 90s were split between a couple VERY cold years and some VERY warm winters (97/98 comes to mind).

The zone numbers do "work" more or less, though. The last decade has been mild, and even the winters that averaged out cold tend to have fairly benign winter minimums - in 2008/2009 overall temps were cold but even Dulles hit exactly zero just once, not below.

I put together a very rough spreadsheet using NCDC image data for IAD and DCA, as well as CAK (Akron-Canton, OH) - the zone ratings on the "new" map ARE indeed accurate. I did an average from '81 - 2010, which I think is a slightly different timeframe than the new zone map, but this is what I came up with for AVERAGE LOWEST TEMPERATURE:

DCA: +9.9 (would be zone 7b/8a which for the Tidal Basin and Georgetown, is probably accurate)
IAD: +0.2 (a solid cold z7 or 6b/7a)
CAK: -6.1 (zone 6)

CAK was "upgraded" from zone 5b to 6a, however, very old maps from the 60s show it almost at a zone 6 even back then. The VERY cold minimums of the 70s and 80s I think skewed the results. Even the 90s had a few cold ones.

At DCA, in the 50s, most winters didn't bottom out below the upper teens, one year never dipped below 20. The 60s were a bit colder, the 70s and 80s colder still, the 90s a bit milder, and since then MUCH milder over all, but no moreso than the 50s as far as winter minimums.

I think, in general, we tend to remember the distant past winters as colder than they actually were, and the recent past we tend not to remember the short-term very cold nights that occur.

My mother INSISTS that, growing up in Akron, OH in the 50s and 60s, that snow "fell at Thanksgiving and didn't melt till March" but the weather data does not support that, not even in the worst winters during that time period, although a few did come pretty close. Most of that was not in the 60s, but in the late 70s though when I was an infant/toddler.

Our memories become altered to some degree over time.

Just to remind, "official" lows that get recorded now in urban areas & airports aren't going to be as cold as there can be a large urban heat island effect. I've seen as much as 10F or even more. So to really compare, you need official records from truly rural areas, but there are scant few of them left. Likewise "official" high temps in cities/suburbs/airports are greater than in rural areas.

I think they finally recognized it, giving downtown DC a z8 rating.

There are some considerations to take into account with heat island, like the weather regime. Winds and clouds will tend to equalize temps across the area, urban and rural, so a windy, cloudy night will not show much heat island, while a clear, calm night will show the maximum head island effect. The last widespread sub-zero event in the I-95 corridor from NYC to DC, in January 1994, was an oddly windy night, so the differences were small.

Since wind tends to keep radiational cooling at bay, imagine how cold some areas would have been without the wind!

January 1994 was the all-time record low in Akron, I was a teenager in Akron at the time. It hit -25F the morning of Jan 19. I remember people losing a lot of plants that never leafed out that summer. It seems that some Acer palmatums perished - the common "Bloodgood" seemed OK but some of the more delicate lace-leaf types died, from what I recall. We lost 3 peach trees - not just the crop, they were killed to the GROUND, but we were in a low lying area, so our temps were probably closer to -30 that morning. Even some Sweetgums and Redbuds had some tip dieback.

FWIW,
Extreme cold can still happen. Locally on Feb 10,2010 the all time record low was set for my closest reporting station at -18F, but the record for that site only goes back to 1950 I think. At my home in a valley, I reached -25.4F that same morning. Definitely the coldest I had ever seen it in Arkansas. Had seen sub zero many times, but more than -10F extremely rare. This cold was possible due to 18-24" of light fluffy snow that fell the day before, followed by a very cold arctic high creating near perfect cooling conditions (but for some wind the first half of the night) that night.
However, these types of conditions are becoming less frequent.

Arktrees

For us, 2009/2010 was a winter of ridiculous amonts of snow, but temps were only a bit colder than average - we never got below the lower teens in fact for an absolute minimum, less intense cold than even a typical year.

The winter before was quite a bit colder, but almost snowless.

I'm always disappointed when I hear people that think microclimates or urban heat islands are "newly discovered" things or things that only few have thought of or taken into consideration. Folks, this is old, old, old stuff and should RARELY effect the "record". We do still need to know what the temperatures are in our cities, so those temperatures are recorded, but it's not throwing off our knowledge of what's happening out there. Rural places still have thermometers! I believe the basis for this phenomenon (the belief that no one except them knows about what's happening out there, when it comes to our climate) is rooted in political hackery.

"Perhaps the "cold winters" your elderly neighbor remembers WERE the late 70s... "

I agree hairmetal. It could be a case of selective or mixed-up memory. Maybe the winter of 61 was cold, the rest in the 1960s were not, but that's her main memory of the era. Also, thanks for your analysis using station data. Knock on wood but this has been the coolest fall for me since I moved here...I hope is isn't a harbinger of a return to the mean for the winter. But means are returned to; that's why they are means. The new USDA map says my low should average to 4F, but it has averaged to 10F since 2006. Not surprisingly though I don't find the minimum to have been the only factor affecting plants. Some years Escallonia 'Appleblossom' has looked ok after 8F and some years it has been completely defoliated by 12F. The duration of cold, amount of wind, snow cover, etc. has made more of a difference. Snow cover is a strange bird: sure it helps for stuff under the snow, but it seems like it can burn what is above the snow due to reflection. I think the winter that was 12ð, the top of the Escallonia that was above the snow was completely nuked by the reflected light. In a year that just dropped to 8F w/o snow, the top had minimal damage.

Yeah, we've been in the 20s 5 times now this fall already...the last few years, we had barely hit freezing a couple times by now.

It was cold enough yesterday morning that much of the remaining foliage on the trees has been freeze-damaged. There's a Platanus (I think an Amer. sycamore) down the street, one of the last trees in the neighborhood to drop leaves - the entire canopy is still green, but crispy as of today when I saw it.

Even DCA has had two freezes - & just tomorrow will be (I think) the "average" first freeze at DCA.

I had been proven wrong on my assumtions of the main post, in case someone didn't want to read the thread from the beginning. I went from the local and weather channel forecasts, although, these below zeros had to be those that don't stay below zero for more than a few hours approx. I never saw it forecasted to go below zero, so assumed it hadn't. I am zone 6b. I need to buy a weather station, I just hope I can get one that is no fuss. They have them at HD and LS. I remember it being colder when I was a kid too, but it was probably not long lasting, it just seemed that way.

I see the humor of the above posts between some posters. I never thought that a weather station was stocked at the local big box store. I have yet to get that weather station. If there are no directions as to where is the best location to put it, do you put it where you think your yard is the coldest in winter? I have a wooden post that is about 50 ft from my house that is fully exposed to north winds, but the coldest should be downhill by several yards. If you go down too much, there is a lake that may make it warmer, or help less hardy plants be okay in winter, or is that not right? I had no tender plants there to test that theory, but I had a Durand oak that is supposed to be lately deciduous, and has held it's leaves since I got it in spring 2012. It isn't right next to the lake, more like a pond, I guess. Can I get some advice on the best location for a weather station? I got my Capital one rewards check! So I can finally buy one of them fancy weather contraptions.

Here's a good guide, explaining the "ideal" while mentioning the "reality" of most yards.
http://www.srh.noaa.gov/images/epz/mesonet/CWOP-Siting.pdf

If you provide a schematic (or better yet, grab a satellite photo from Google), I could give you a good idea about the best place to put your station.

Here is a link that might be useful: Weather station siting

I think that rock weather station is as high tech as I was hoping for. The one in New Jersey is low to the ground, and do-able to me, but the ones about 30-40ft tall isn't anything I would ever attempt. The info on the Wunderground personal weatherstation close to Uniontown posted above by Famartin may be the way to go, and to get a min/max thermometer as beng mentioned way above in this thread. The few results for the last 2006-2012, 6 years is close to what I thought, with the exception of the minus zeros, which may have lasted a few hours. Sorry to have people try to help with the details and I go the simple route, but I think a weatherstation about 4-5 miles away and a min/max thermometer, if you can retrieve the data from hours past, would be good enough.

david,
Late to follow up, but you mentioned the effect of snow on potential damage. This is a very real effect. Reflect may be a part of the problem, but IMHO, since snow is such a good radiator of heat, while insulating additional heat coming from below, it seems very likely that the coldest air will be just above the snow level. Temps are supposed to be taken at 6' above ground, but much can happen between the ground and 6' especially if there is a thick layer of snow. Anything below the snow line will be insulated from the worst of the cold. This can lead to odd results.

Above I mentioned our -25F morning in 2010. That spring, all forsythia flowers were killed above the snow line, but those below flowered as usual. Very odd looking. Took me a few days to realize that had happened. Native Sumac was killed back to 2-3 yo wood ABOVE the snow line. Our Viburnum that is very cold hardy, was basically killed back to the snow line, even though is should have been fine with the recorded temps. It budded weakly above the snow line, but eventually died back to the snow line. There were others, but you get the ideal. It's micro-climates (like being in a cold valley as I am, but micro-climates in micro-climates as well.

Arktrees

arktrees, I've posted this before, but season-long snowcover can allow a tiny planted Norfolk Island pine to survive a z6 winter. Note the main stem was killed above the snow (the brown), but it sprouted from below, where it was covered:

Seriously? That's pretty nuts beng. Never heard of anything like that before. What winter was this?

Beng I got a kick out of that. Also reminds me of Ellen Hornig who kept a few zn 8-ish South African plants alive through the winter...becuase her NY snowbelt location was often under 6'+ of snow all winter. Also shows that this species, even though it comes from a place that has never had a frost in modern times, is very cool-tolerant. Which is also demonstrated by the fact that there's an established specimen on Isole di Brissago, Lake Maggiore, southern Switzerland. This remarkable area has 4 well defined seasons, and a winter with highs around 44F with not infrequent snow showers, but is in the very most sheltered areas like the island rated zone 10a. Most of the immediate coastline of the lake is zn 9 and gardens feature Phoenix, Citrus, Bougainvillea, etc. Meanwhile because they have a winter, most any typical temperate climate plant like peony, iris, lily, etc. grows just fine too.

EXCELLENT example beng.

Arktrees

famartin, it was the winter of 2002-2003 in west MD. It was mild until mid-Dec, then a major snow (2 ft), and snow continued off & on that kept bare ground from showing until prb'ly late March/early April. An unusual winter & the ground beneath the snow never froze.

I saw it planted in the ground the previous autumn & laughed at the absurdity. Next summer I saw it, thought I was going crazy & took the pic.

Now that is fantastic, I wish I could manufacture some snow, and put it around my palms. My Norfolk Island pine is our Xmas tree, for the last 2 years. I did finally get a min/max thermometer today. $14.00 plus tax and batteries, about $24.00. I put it about 20 ft from the house, because the snow made me not go out too far in my Crocs shoes, which I love to wear year round. Once it dries a bit I'll move it about 25 more ft, to where my favorite Live oak "late drop" is growing. It looks okay, I just had to look at it although from a distance, it looked nice and green with the backdrop of white snow. The one in my front yard only 25-30ft from my house is still perfect looking. But we've only had one night of 12F. We were forcasted several teen temp nights, it changed to the 20's instead. I now can keep track of the overnight lows. The other info wasn't of much interest to me anyway. The wind chill temps may be interesting, but I am happy with this now, anyway. It is currently 22 F.

Poaky and Beng,

Photo of a Norfolk Pine forest in Kauai, Hawaii I took - I'm really shocked they are growing at all in your areas.

We don't get a lot of snow in the winter in SW Missouri, it's our dry season, but on cold nights I will coat various trees - mainly very young ones with ice and protects thems fairly similar.

{{gwi:329298}}

I have seen the NIP growing in Florida too. It's odd how they are in an outdoor setting, vs indoors. The needles change in orientation, upward outdoors and downward indoors. I thought mainland Florida would be too cold for them, but I saw them growing there, as well as the Florida keys. Joeinmoe, how do you coat them? You surely aren't covering NIP, planted in-ground in your yard and overwintering them each year? Are you covering them with ice or I have really misunderstood your post? I've had a bit to drink so am more dim-witted than usual. I have 2 "hardy" palms in-ground, which are covered. I have one that is potted, which is indoors. That would be great if have overwintered NIP, in-ground, joe. If you have time go look on the Tropicalesqe forum. There is a guy on there that kept a palm alive for many years in zone 4 Utah, I THINK. He finally couldn't do it anymore, it got very large. I would say 10 ft tall before he stopped covering it. His posting name was Arctictropical, I am 80% sure of that. He had covered them with a styro box and used lights wrapped around the palms. If you have some spare time look on the Tropicalesque forum. Arctictropical I am pretty sure is the name. If not it is similar. Boy, I have gone really off topic here. The posts about the overwintering of some hardy to zone 7 -8-9 may take a while to find, but the guy on here has done it in zone 4, for years. That is until his windmill palm, zone 7 hardy got too large for his enclosure. I have 2 palms in the ground, I already mentioned, but it is only covered by burlap. I may try to overwinter a palm or 2 in the winter of 2014-2015. I will have to use those that grow slow close to the house. Has anyone over-wintered any tree for several years by covering/ artificial means for more than 4 years?

Hey Poaky,

Nice having a little something to drink :). sounds fun.

No I don't have Norfolk Pines growing, what I meant was we don't get much snow here, but we are probably one of the worst places in the country for growing peaches and Apricots. In the month of February we might hit 70's- 80's for a week at a time, it causes these trees to bloom way too early, then we might get a low near freezing killing the blooms. So if that happens I coat the trees with water during the low temperatures to protect them, much like Florida Strawberry and Orange growers do and it creates a coating of ice - works great. I have no palms, but in know a couple cold hardy varieties will grow here like the windmill etc.

Well Joe, I have a peach tree in my zone 6 yard here also. We don't protect it, but we get lots of fruit each year. They never get large and plump with fruit, but the branches are low-hanging with fruit, my dad wanted the tree or I would get rid of it. I wish someone would take the fruit each year.

FTR,
Got to -3F at my house this morning with far from ideal cooling conditions. Could have been MUCH colder had clouds cleared completely and quickly so that we had ideal cooling. I think I will be staying with USDA Zone 6b.

Arktrees

arktrees,

Interesting, you must be in a hollow, because we only got down to 6 degrees just south of Springfield, MO, but according to our weather guy thats a record for this time of year.

Joe,
Yeah, I'm in a cold spot. There is a hill 500-600' higher than my location about a quarter mile west of me. Once the sun goes behind that hill, the temp FALLS FAST. That, and 9" of snow/sleet were major contributors. When we first moved here, we put a thermometer up, and thought it had to be defective. Then I started going to evening/night walks and discovered "yeah, it's really THAT cold". The biggest issue I have with it is late freezes. Man does our stuff get knocked around with those. The big April 2007 freeze after an extremely warm March yielded 12F at my house. Killed several new plantings outright.

Arktrees

This post was edited by arktrees on Sun, Dec 8, 13 at 22:35

We have yet to go to below zero F this winter. We have been in the teens, 13F as our low this winter. I have a min/max thermometer now. Ours will likely get lower at some point. When I say "we" I mean what my min/max thermometer says not other sources, although, they are usually the same or close. Wind chill not known though.