Oh just played today, air temps around 51, no wind, painted cement courts.
Hadn't touched a racket for 3 weeks due to PuertoRico vacation.
Hit 40 serves with 8 month old DunlopHDHardcourts, bouncing them around mid thigh on the good ones, barely ankle high on bad ones, at the backboard.
Guy opened a new can of ProPenns. EVERY single first flat serve bounced around bellybutton heights, some higher when pronation was nailed, and even a few safe second serves would have hit the backboard 21' behind the baseline at that height. Most second serves were going around shoulder heights to a 6' tall opponent. Couldn't hit a twist to save my life.
Arche3 can verify that today was around 50 degrees.