Joined: Aug 2010
Posts: 12,727
Likes: 2,105
From: Madison, WI
Bikes: 1961 Ideor, 1966 Perfekt 3 Speed AB Hub, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, 1980s Bianchi Mixte on a trainer. Others are now gone.
Another option to consider is a pair of wind pants. They are not waterproof and are breathable. They will not keep you dry but they can add warmth if the temperature drops and it starts raining. And being quite breathable, you would not accumulate sweat wearing them.
I have a pair that I use for warm weather backpacking for trips where I only bring shorts, not long pants. I can put the wind pants on over the shorts for chilly wind. Mine require shoe removal to put them on, they are not designed for cycling. I have not used them for cycling, but I bring my other options (listed above) so I do not need them for cycling.
Mine pack to about the size of a tennis ball, I have had them for over a decade.