It seems to be more common after the update.
There was a thread a few months ago about this phenomenon
And I say..... bring it on! I love rain on the island.
Yeah the island raining is actually so much cooler then when it rains in town. Because when it rains on the island, the music stops. All you hear is the pitter-patter of rain on sand, while the ocean waves roll in. It's very soothing...maybe an occasional caw from an unseen seagull (but I might be making that one up)