...When it's 60°F and raining?

I ask because I had one guy tell me he went totally based on temperature, ignoring the other conditions. That doesn't work for me; I'm cold in windy, rainy weather if I wear a jersey and shorts the same as if it was sunny. This morning I wore a waterproof jacket (for 5 minutes of rain - bah!) but was way too hot even with the vents all the way open by the time I'd ridden 13 miles to work. Not sure what the best solution is.

Maybe a bike umbrella? Or my own personal bubble?