I use a couple of online weather sites to get some idea of what to pull out for the next day's ride (I like to have everything ready to go for the morning to minimize stumbling around in the dark).
On occasion I will notice the actual conditions at 6-6:30 AM to be different than projected, and will make adjustments if need be.

Other than that, I try to ride every day regardless of weather (I have made some exceptions) unless I'm sick or have some other compelling reason to not ride.