The tip from Travis is not only a cold weather tip, but all season moile trapping tip. For the past couple years I've used nothing but peat moss for covering mole sets. I carry 2 buckets, one with traps and flags, the other with peat moss. The peat bucket has a lid.
I have had great luck using the peat moss in rainy conditions, as it eliminates the "blob" of mud that forms if you use the dirt from the excavated hole. I used to cover the sets with heavy leaves if rain was predicted, but now use the peat all year. I can honestly say I feel the moles are actually attracted to the smell of the peat moss and it improves the catch rate. Think about it.... where are the moles when people have peat and mulch around their flower beds and foundations?
Here's a couple pics from today. Set up yesterday in 40 degree temps with a winter blast kicking in. Within 2 hours of setting, temps dropped into the 20's and rain, sleet, and snow covered everything. However, the traps worked perfectly and I caught both moles working the property, one on each side of the home. So weird, as I also caught muskrats from a pond on the same property and had to break them out of the thin ice. Moles and muskrats.... what a strange combo!