I know it was this morning but if anyone ever wonders when the rain might stop and you've got a smart phone - go to weather.com and type in where you are click on the radar. (ie: Magic Kingdom Orlando FL)
You can watch the rain arrive, when it's raining and you'll also see when it's leaving the area. You will have to refresh a few times but it's always been pretty accurate for me. One time I saw the rain was nearly done so we stuck out the wait, another time I saw we were right in the center of it and it would be awhile still raining so we bailed and went to an indoor ride instead.