After pondering how to leave a trap set up in the rain, I came up with
a VERY simple and effective solution!

If you have a medium to large size pet carrier, take the door off (this
shouldn't be hard to do).

Then, simply slide the trap inside the pet carrier! (Of course, you
should be sure that the entry to the trap is sticking out of the pet
carrier. Duh!)

You now have a solid roof over your trap, along with ventilation on all
four sides so that the odor of the bait can be spread all around.

I did this last night and it worked like a charm! I caught a cat...but
it wasn't my beloved little Albert.  :-(

Not YET, anyway!