I'm with Kim. I also live in Canada with humidity highs in the summer to very dry winters. My dehumidifier is set to kick in, above the 50% range. The shop humidity usually stays within the 40 to 50% range.
With the humidity gauge that I have, that range is optimal.
I know the extreme humidity you guys get in Ontario and we don't come close on the bald ole prairies.
Without any heat in the basement shop, temperature stays around the 50 mark until I turn on the space heater. Outside of the shop, the rest of the basement stays around the 60 to 65 mark. Any of my shaft wood have never suffered because of these temps.
I also store my cues downstairs. They are close to an outside wall. I check in on them every once in a while. The cases seem to keep them protected temp wise and have had no problems thus far.