Today was colder than it has been for the last week.....46 degrees. Lately it's been in the upper 50's and low 60's in the afternoon. The only time I wear a jacket is if it's pouring down rain/snow or below freezing.
I hate jackets.....too hot. I prefer wool layers....they breathe and still keep you warm if they get damp. Today I did 62 miles with a lightweight wool base, a midweight wool shirt and poly- jersey on top. Was plenty warm. Back in February I did some rides and a race in the mid 20's with no jacket...heavy wool.