Our weather at the moment can best be described as typical April showers which will hopefully bring out lots of May flowers. I had always thought this line was from a longer poem about the weather of each month but I cannot track it down. The best I can do is find is this reference from a poem written in 1560 in a book written in 1860 by T.Wright:
Aprell sylver showers so sweet Can make May flowers to sprynge.
This got me thinking about other weather sayings of which there are plenty more both generally and specifically for this time of year: