Colder weather will cause increased resistance in the power steering pump, etc.

Belts transfer power and grip the "v"-pulleys - not by the "tightness" or tension of the belt (although a certain amount of tension is required) but by the belt being expanded as it curves around the "v" pulley.

Check your owner's manual, there should typically be 1/2 - 5/8" slack on the non-tension side of the belt (the side that is not under tension).

If the squealing is ongoing, replace the v-belts. Usually the friction surfaces of the belts get glazed and the squealing is caused by slippage. Rather than trying all sorts of remedies (sprays, roughing the surfaces, etc.) the squealing is a good indicator that the belt is nearing its life end. Replacing it now is inexpensive assurance that you will not suffer an alternator outage or loss of power steering in traffic, or on some deserted backroad at night in a blizzard (that is the most common place and time for such ocurrences) :)

Happy brikken