No A/C here (NH) and, yes, it can get too hot to quilt, piece, get dressed, or even think about sitting down at the sewing machine.
When it's hot AND humid, forget it. What fun is it to be sticking to the fabric every time you put your hands on it? And how grungy does that make the finished blocks? Ick! Nope, some things are better left for another day and, luckily for us, those hot sticky spells up here never last very long at all.