When I was little there were two things that would guarantee an unforecasted mid-summer rain:
Mom putting several loads of laundry on the clothesline, or
Dad mowing down forty acres of alfalfa.
Nowadays it only happens when the Secret Service detail washes and waxes Al Gore's limo!
That is funny because I just heard from my Missouri daughter and she says that it rained there because her husband has 40 acres of hay down. And she always hangs her wash outside, but didn't have any on the line this time.