Now, I don't know anyone who does that kind of crazy thing.... Hehe.... that's ME!
I live in central Florida. My house is "cooled" to 81F which is 27.2C and my darkroom tends to be just a little warmer than that. Temperature doesn't fluctuate much as that's where my thermostat is set to. Tap water (which I dilute my Dektol) is a bit warm too, so the temp fluctuation of the developer is not great. I actually have not observed any meaningful difference.
Taking Bob's advice, it's probably a non-issue provided you let your developer reach an equilibrium or close to it, before you start your process.