I think temperature is really more individual in how it effects a person. I have Raynaud's Syndrome and get cold pretty easy. I love the heat and tend to ride much faster when it is warmer. Normally I ride very early in the morning so not high sun but dew point can be pretty high in Illinois is summer. I find the colder it is the slower I start and I never get quite as fast. Sometimes I run 2-4 miles before and jump on bike that helps even more.

I am probably the only person who easily can ride my trainer full out for 95 minutes in the basement with no fan at all on. I don't even take a drink. There is a pool of sweat under the bike but frankly I think temp as I say depends on person. I might add the opposite too I do ride even in winter outside when it is cold as long a not real windy. My feet just go numb.