Also, and this is going to sound
dumb, wearing the right kind of jersey and/or shirt under your jersey makes a big difference.
The worst experience riding I had resulted in a mild case of hypothermia……at 96 degrees and near 100% humidity. A friend and I went riding out to and around Stone Mountain east of Atlanta. It was a fun ride, but we had like 3 or 4 flats between us over the course of what we call "the fail ride." Those trails just aren't maintained. We decided not to risk riding back on those trails with no supplies to fix flats left (we went
through several cans of tire sealant, a tube, a patch, and a couple CO2 canisters). We stopped and called a friend to pick us up in his truck……and I started getting really sick. I called my sister (a retired Marine and avid runner & cyclist) to talk about it, and I ended up stripping down to my shorts and lying on black tarmac and then riding laps around the parking lot to keep my body temperature up around normal. We found a hiker who had some disposable thermometers and my body temp was around 95-96 before I started that.
Since then, I've always ridden with a rash guard (made for grappling) under my jersey……it wicks at least as well as not wearing it and helps maintain heat when I stop riding. I don't ever want to feel that again.
So……it's very important to keep yourself from overheating. But, when you stop riding, it's important to keep an eye on how your body is responding……if you just stop and are covered in sweat and clothing made just to keep you cool, bad things can happen.
Also, Chrome doesn't make them anymore…but I have a Chrome merino wool jersey that I
love. It's perfect for riding in anything from about 45 degrees to around 70 degrees. Wool is awesome…it regulates temperature very well, is naturally anti-bacterial, and keeps it's temperature regulation when it's wet. They make the best socks in the world except that they don't last as long as they should for like $8/pair.