what can be done to stop my drive belt squeaking when it rains?
A new belt does the same thing.

 

If its tightened properly and still does it, I picked up a neat trick for making squeaky belts quiet while working at a radiator shop. Candle wax. With the engine running (careful of the fan) press a candle onto both sides of the belt until it almost starts to turn white. Put the candle on the end of a stick to be safe. Fans really hurt if you stick your fingers in them. The candle wax stays embedded in the belt and stops the squealing. It worked every time for me

 

My belt squeels like crazy in a power car wash. and i loose all accessories. no big deal. jeep never shuts off.

 

some new belts don't fit the groves right you might try and different brand