Date palms will indeed live in zone 8, even in a very wet one, as our winters are here. I have had CIDPs and Medjools in the ground here for years. I have seen young CIDPs take 15 degrees with no protection and make it, although they were almost completely defoliated. So I guess while it's not a good idea to say they "thrive" in zone 8, it's not necessarily untrue!

Here is some of my personal experiences with a few (established in ground 1+ years) palms and minimum temps in a humid, wet environment:

Young medjools 4ft tall good to 20 degrees unprotected with no defoliation; some leaf burn that went away a few weeks later.

Young CIDPs 3ft tall good to 18 degrees unprotected with no defolitaion; survived 15 degrees with no protection.

Young queen palms 4ft tall good to 24 degrees unprotected with no defoliation; survived 19 degrees with no protection (barely!).

Young windmills (2ft) and pindos (2ft) good to 19 degrees unprotected with no damage.

Young sabal palm (1ft) good to 20 degrees unprotected with no damage; spear pull at 19 degrees with no protection.

Young Owari satsuma orange trees (3ft) good to 26 degrees unprotected with no damage; defoliation at about 22 degrees; survived 19 degrees.

Durations on these freezes usually about 12 hours or so; never more than one night without temps getting back to at least slightly above freezing the next day.

HTH

I think many nurseries push the numbers a little bit. Some sites make it sound feasible to grow Trachys in zone 6 without protection.

OTOH, I've had a date palm grow from seed to a nice tree by spending 3 years on a NYC fire escape with no protection or anything, I didn't even water it, it just grew. But stupid me - at year 3 I finally brought it inside out of fear and killed it. :( It was massive though.

You're doing well! I have a Satsuma in ground that has made it to 19 degrees, no damage. Last winter it was covered with ice. My Windmill came through with no damage at all. My sago had only one frond turn yellow.

Some nursuries fudge the numbers a little. Canary Island date palms can tollerate a Zone 8b winter, but not much more without some sort of microclimate or protection. I have never seen a segegal date palm survive past a zone 9a or warm 8b, but true date palms have been reported to survive in a zone 8a. Stone gate palms are related to the windmill palm so many believe they can tollerate zone 7 conditions. This might be true, but the palm still needs more testing. European fan palms will not survive a zone 6 without protection. The blue form has a chance of one day maybe going unprotected in a zone 7, but the green form will get very severe damage if temperatures go below 10 especially for several or long durations.

Since I planted my windmill this year it survived 20 in early march without any damage. Also I accidentally left my queen palm outside during its first winter behind a shrub until it realized it was outside sometime in late december. Went through several low 20s, probably a temp or two in the upper teens and looked awful, but survived.

If you want accurate info about palms you should probably look on a website that does not sell them. SOME do lie a little with their cold tolerance.

Good followups guys!I would just add that individual plants vary quite a bit,I had 3 palms get spear pull from early Nov warmth (70s),followed by rain and 18F(2 wag/fort, 1 Naini Tal)Fortunei and Wagnerianus were undamaged,1 wag/fort died and the other 2 have recovered from spear pull. Sometimes hardiness is as hardiness does,all the rest of the Trachys,etc survived multiple single digit temps after this with no problems and not much leaf damage some none at all,I should add that all were covered and did not have frost formation.

Misinformation? On the Internet? I am shocked. SHOCKED!

Davesgarden.com

Yeah I'm shocked, misinformation by internet sellers? Just look at some of the garbage TyTy claims. Another, Paradise Palm Co states right on their site that trachys and needles are good down to zone 4!! Really? That's great! Well I guess I won't be having to cover mine this winter after all then.... NOT