*FWOMP* Here's a few days in the 90s for ya!
Once again I'm really glad I have air conditioning thanks to the heat pump I bought to replace my dying furnace. And this week especially, I'm really glad to have the extra ceiling fan I bought for the main room in the basement, after seeing how cool the one the insurance company bought for the guestroom looked.
The basement is actually noticeably cooler than the upstairs no matter what, but having that little bit of air flow downstairs makes the basement feel cooler still, and makes me need to do less cooling of the whole house to stay comfortable during the day. Working downstairs nearly all day means it matters much less how warm the upstairs is, as long as it doesn't get so hot that I have to spend money knocking the temperature down anyway.
I've done a lot of opening windows and even the back door when it's nice and cool in the evening, but I have to be careful about leaving the back door open, especially with repeated reports of break-ins -- yeah, even when people are home.