My shop is about 50m2/500sq ft. It's isolated and i have a heatpump/aircondition unit, so temperature stays in the 19-24c range year round. Humidity hovers around 40-50%.
If you have an uninsulated space, I think the first order of the day is to try and insulate as best you can, not only to get a more even temperature, but also because many of the chemicals we use don't like cold temperatures.
I'm in Norway, pretty far south, so winters are usually fairly mild, but in 2023 we had almost 4 weeks of -16 to -28c, so it can get very cold. Summers can get hotter than most people think, we had a few weeks of 35c this summer and many days in the high 20's, so there's quite a bit of variation through the year.