Well, I am in the tropics so I don't heat the etchant. Coldest is about
24 °C. I do etch on top of a bar fridge where I keep my solder paste and
assorted acrylic glues & sealants. So it's probably a little warmer
based on the condenser coil heat at the back of the fridge.
Also, I use diluted nitric acid. One full gallon carboyle of the
concentrated stuff lasts me about 10-15 years after dilution. Space has
a bit of forced ventilation with a BLDC plastic 115CFM fan.
The nitric fizzes/agitates on its own when etching and the copper clad
rises and falls a couple times a minute if double sided as bubbles build
on the bottom. I use a 1 litre rectangular plastic container (3" tall)
with a lid usually about half full.
Details on the whole process with pics and videos.
https://hackaday.io/project/7938-pcb-smt-maker-lab-homeAncel