Cold can be manageable, rain can be manageable, but for me cold+rain = stay indoors.

I recently took a first-aid course taught by some local EMTs. About half the class focused on bicycle-related injuries. One thing they mentioned was that you could develop hypothermia in relatively warm temperatures if your clothes are wet. They recommended keeping a mylar blanket in our bike bags. I already do that for non-summer rides, and I recall someone else here once mentioning that they have one, also.

I'm glad your ride turned out okay.