People have mixed feelings when it comes to winter. Some love it, and others don't. Roofs, on the other hand, don't have mixed feelings as they hate winter! 

If your roof wasn't installed properly or if it has aged there are a handful of issues that we see time and time during the winter. Be aware of what can happen and be sure to take immediate action on the below issues:

Attic Condensation
When your attics surface is cold and it makes contact with the warm sun, condensation can occur. If your attic and roof are not properly ventilated, your roof can grow mold and even lead to small leaks. 

Ice Dams
Another issue that poor attic circulation results in is ice dams. This occurs when snow and ice melt at the top of your roof and meltdown towards the edge to simply freeze up again. This can cause all sorts of problems from water leakage to gutter problems. 
Strong Winds & Snow
Wind and snow that naturally attack your home can give your roof a beating. Also, indirectly this snow and window can cause neighboring tree limbs to break. Be sure to trim any branches that you see hanging over your house. 
Flashing Problems
Flashing on your roof are the metal strips that get placed between corners and ridges such as your chimney and skylight. Snow and ice are some of the top culprits when it comes to flashing problems.

All in all, roofs and winter do not get together very well. Make sure that all installation work and repair work gets done by an experienced contractor and that all issues get resolved as soon as possible.