Problem is too much humidity and the ceiling is cold near the exterior walls. When water vapor touches something cold it condensates and appears as water on the ceiling. Happens sometimes at my place when it gets super cold and when I forget to turn on the bathroom vent. I plan on addressing that this summer by spray foaming the exterior edges of my attic underneath the soffit vent baffles (hopefully to keep the ceiling warm and to allow the attic to vent properly still). My roof is not the tallest pitch so there is not much space for proper insulation at the edges. I had put some batt underneath the vent baffles but that appearently was not good enough so now I will spray foam there.

If you keep the doors open, the air returns will be able to circulate the air much better to equalize the humidity throughout the house. But I agree there is most likely a deficiency in the insulation.
The bitter cold should begin to break in a few weeks.
Casey

Agree with the analysis above.

But as a Canuck from our Banana Belt, I can't resist: Not all that cold. At night, we're dipping to -18˚F.

Get up in your attic and check, quickly. We are also in southeastern PA. We recently had this problem and up in the attic it was raining, wetting our attic insulation. We had a warm house air infiltrating into the attic, causing the attic roof undersides to condense in the very cold weather, raining down on the insulation, negating the insulation value. We rented a thermal camera to find the infiltrations and block them ($6 can of foam) and it solved a potentially VERY expensive problem, both of heat loss, but also of wetted insulation and ceiling below it.

not enough info.
I'd start in the attic. look at roof decking
for condensation, or leaks. the moisture
can enter high & exit low.
then look at insulation above wet area.
is it wet?
move the insulation back & inspect the
attic floor in this area.

look around. is there a supply duct, or bath
fan in this area? is it wet around or on the duct/supply
box or bath fan?

any recessed lights in these areas?

what is outside of the exterior walls at
these areas of moisture?
balconies?

take some pics & post back.

I suspect the frost on the windows is due to
added humidity.

best of luck.

I am not able to get to the attic so for the spring I was thinking of finding some sort of reputable energy audit company to come out and make reccomendations. I am also having my roof inspected since, though fairly new, we had an usual hail stor last may...everyone is suddenly get their roof's inspected so It can hurt I guess. I shut the humidifier pretty much off. Humidity dropped to 20%. No more frost on windows. No more condensation on ceiling. I am not saying there is not some sort of deficieny up there...just that I seem to have solved the immediate problem..though I now get the static hair complaint. When it get back up into to 20's I'll start the humidifier back up and see what happens. We have been here 8 years and this never happened...then again its never been this cold for so long either...

Well, I turned the humidifier back up...Woke up with 30% humidity..a few windows had frost...not as many. The one room so far is fine. The bath again had some condensation. The temp was 1 outside...feels like 20 below with wind chill.

1) Is it unreasonable to expect 30% humidity in these conditions?

2) I am measuring humidity on the first floor...would it be higher in the second? I guess I could move my stat upstairs.

3. SInce the moisture was again at the edge of an exterior wall..is this where insulation is lacking..I thought soffiting would be here and less insulation?

4) What kind of professional should I call in the Spring to size up the attic?

5) Funny, I always though if I were to do something it would be to rip out the garage ceiling below our bedroom and have it spray foamed to make my bedroom warmer...never thought I'd have an issue at the other part of the home where its warmer.

Two things come to mind:

1) Water backing up on eaves. But that happens when it gets warm and snow melts but is dammed up by ice dams. And it has not been warm!
2) You have an area of your ceiling devoid of insulation above it - this could have been caused by a rodent or other critter. This ice cold patch could then condense out water vapor. This seems plausible. To test, get a step ladder and feel the temp of the area dripping - is it ice cold compared to the rest of the ceiling?

Why can't you get in your attic until Spring? If you've got some sort of leak going on, I sure wouldn't want to let it fester for another month or two. Cut a hole in the ceiling if that's the only way in, and get it inspected.

there may not be enough insulation in the area..getting to the attic involves removing everything from a closet... then going up and moving around thru blown insulation hiding the rafters...this is better left to a professional ..
I see no outside damage or evedence of an animal...if there is an issue its been there all along.

Re:

1) Water backing up on eaves. But that happens when it gets warm and snow melts but is dammed up by ice dams. And it has not been warm!

How would this cause condensation on th edrywall ceiling in the room?

Re:

2) You have an area of your ceiling devoid of insulation above it - this could have been caused by a rodent or other critter. This ice cold patch could then condense out water vapor. This seems plausible. To test, get a step ladder and feel the temp of the area dripping - is it ice cold compared to the rest of the ceiling?

It is cold in this area..just not sure how the insulation moved...no signs of rodents or damage outside the house.

So who do I call to get up in there and check thigs out? Roofer? Insulator? Energy Auditer? Other?

Water backing up would not cause condensation. It would be water seeping through the drywall. Often it will have the same appearance as condensation. But if this is happening you would also see some sagging. I see you mentioned the surfaces were cold. Then you need these places insulated - any carpenter or a handyman could take care of this if it is batting insulation. If it is blown in insulation, then you should have a person with the proper equipment get insulation where it is needed. With regard to the cold spots, perhaps these were just voids that were always there but is only now causing this problem with the sudden cold spell.

And until you get this remedied, you should clean the areas that get damp with soap or disinfectant so mold does not form.

Humidifying a home may improve the occupants' comfort, but it can cause some unintended consequences like the ones you've experienced. Another potential problem you may experience is condensation on the back side of your exterior wall sheathing.

I suggest that the safest option in the short term is to turn the humidifier off and leave it off.

You need to be able to inspect your attic, figure out how to get in there. It is an important thing to know. As far as insulating near the edge at the cold spot, its going to be easier to insulate those areas near the edge by accessing them from the soffit if you dont have high pitched roof, otherwise you would have to move or crawl through the insulation to get there.

Turning down/off the humidifier helps. One the temp is in the 30's again I try to turn it back on and see if the problem returns. This is the first year we have had such extreme temps since we lived here.

I will get the attic checked. I can not get to the soffits outside the house...too much snow and we have a 2 story - I can't get up that high.

As far as inside....I explained that I personally can not risk moving around up there since the rafters can not bee seen...I'll end up falling thru with my luck!

So what will be different in the spring that will enable you to inspect the attic?

Take a piece of plywood up there and lay it down over the rafters/on top of the insulation and make a path to the edges.

Plywood idea works for walking/laying on, except move the insulation first assuming it goes higher than the ceiling joists (I would hope). If you put too much weight on the insulation it will push out your ceiling drywall. You will probably need to move the insulation anyhow to see where the joists are so you can walk on them.

I can get a professional to come out in the spring...roofer...insulator...energy auditor...not sure...right now no one is interested...I know my limitations...if I did not have to shove a foot or more of blown insulation aside i might try...I don't feel safe ..