I just read the Andersen Limited Warranty and Specific Additional Exclusions list "Condensation".

It is definitely from condensation and I only noticed it in the coldest days of winter (I live in WI where it can get to -20.)

So my humidity levels inside are too high? We have more trouble with dry air in winter (chapped lips, dry skin, static).

I heard wood windows require maintenance. Should I be putting something on the wood to protect it?

Keep humidity under 35 percentage in the Winter months!. Otherwise you may get condensation on the windows.

Used to live in MN. Also, your cellular shades are likely trapping moisture behind them, and adding to the problem.

Shades don't as much "trap" moisture as much as they limit circulation and therefore contribute to the surface temps dropping below dew point. The air behind the blinds has roughly the same moisture content as the air in the rest of the space.

I have a barometer and will keep an eye on the humidity in the house. I did notice this isn't a problem for the sliding door or the one stationary window we have in the house, only the ones that crank out.

You are locking the windows?

I am locking them. They are not opened from November to March because it is too cold out.

Probably the shades as described above. More circulation of warm interior air= less condensation. The warranty verbiage about condensation refers to the fact that the window is not warrantied against having condensation, since there are many external factors beyond the window itself that can cause it. The wood rot, even it from condensation (almost always is), can be covered under the warranty if they are properly finished and maintained.

May have been an autocorrect error, but you need a hygrometer, not a barometer to monitor humidity.