Like lots of members, my '79 Corvette (L-48 / TH-350) is waitin' the winter out in the geerage. Mine is detached and unheated with no electricity.

The temp really won't have much effect...the trans is prolly leaking anyway. There are many places for the trans to leak, so locating it is the first order of business...trans fluid will "wick" around to just aboot every place you can think of. The best thing to do is clean it off really well, and see if you can find the originating leak.
Truth be told, 99% of ALL automatic transmissions leak somewhere. Small amounts of seepage is to be considered normal, especially on our older cars. The trick is finding it, then fixing it.
Also....be sure what you're seeing is not power steering leakage...they have a tendency to leak too...

Thanks for the reply, Joel.

Depends on what part of the PS system might be leaking. The steering ram goes from the DS to the center area of the car, under the engine. If the ram seal is leaking, it could run towards the center, and drip off right under the engine oil pan, and look similar to a trans leak. Never hurts to check.
We get cars all the time with leaks that other places just can't seem to fix. As I said, the trick is locating the source. A lot of times, it's a PS leak, other times, it's engine oil, or coolant leaking. Sometimes it is a trans leak...ya just never know. The best thing to do is clean it off really well, drive/run it, and then look to see where the leak originates from. That determines how to fix the leakage.