Hard for me to quantify & others might disagree, but where we used to have a day or two in the nineties once or twice a summer, I'd say it tends to happen more like three or four times and lasts for several days when it does. Fewer people get by without air conditioning of some sort now, where it used to be quite rare. I'm in southern Maine inland from the coast about 20 miles and bear in mind it's usually cooler on the coast than inland in summer.

Honestly, you're right, it probably won't seem that bad to you. The last time I went to Florida, I couldn't breathe for two days, it seemed so hot to me, and that was in February.