Why does my battery go dead

It may be related to the rain not the wipers being turned on

If the wipers do not fully park this cam cause them to kill the battery.

Water conducts electricity. So most likely you have a bare wire or bad connection that when it gets wet creates a short to ground, completes the circuit, and turns something on until it dries out. It would have to be something that's not switched off by the ignition switch when you shut off the engine. My first suspect would be the wiring in the doors or the trunk. Many years ago I had a car that would do the same thing. When it rained the battery would go dead. I discovered, at night, the interior lights were on. It was because the wire going to one of the doorjamb switches had a bare wire. When it rained and the wire got wet the water completed the circuit to ground and the interior lights came on and stayed on until the battery was dead the next morning. Hope that helps! Jim