Climbers use many tactics to send harder. The nice thing about tactics is you don’t have to be any better or stronger, just smarter.
I love climbing in the Summer, but it’s hard. Rubber and skin friction decrease with higher temps. I’ve been climbing a lot in colder weather, here are some tips to make it tolerable:
Bring: Chemical hand warmers, gloves, a down jacket, thermos w/ warm drink, hat.
(side note: There are also chemical cold packs you could use to cool you skin in the summer)
Stay: Close to the car, in the sun
Climb: Boulders (your hands are on cold rock for shorter periods), in the afternoon when temps have risen.
Went to a new (to me) area today. Red Rocks (of Boulder) is a group of fins on the outskirts of Boulder. 
We found a little unclimbed (?) boulder. The left and right sides are easy, with a fun center line (maybe V2-3).
Talk