it could be 3 things. Ive had this happen on my 2001 in march and it was VERY cold outside too and it stayed down... talk about a freezefest.
If you believe the fuses are okay, then i would narrow it down to either the window regulator cable went bad. then again, the window would simply fall out down
Most likely it is your window motor. if you are savvy in taking the doorpanel off and have a good idea of what to work with inside the door... take a new window motor and pop it in. .
Before you go into replacing the motor though, just to see if the window wires are good or bad, (which is odd) then maybe you could test the motor with other wires and a switch. im sure one of the other members here could tell you how to do that, i have no idea.
not the best of answers im sure, but its a start. hope this helps