I did a small show yesterday. My enthusiasm for it started to fade mid-week when I learned that it would likely be 100°F the day of the show.
Early in the show, TWO shoppers said they'd heard it was only going to be in the 80s, so that improved my outlook considerably! It was VERY pleasant with a gentle breeze until about noon ... and then it heated up VERY quickly. By 1pm, it was close to unbearable.
My booth neighbors had a huge ice chest full of bottled water and offered me a few bottles throughout the day. I'd brought water, but all I have is an insulated lunch bag and the ice pack melted very quickly, so my soda didn't even stay cold. They also treated me to an ice cream cone mid-afternoon!
I'm sunburnt, but not as bad as I expected. I had sunscreen with me, but all I could get out of the can was propellant (or something!), no real sunscreen. Had a canopy, at least, so that was good!
The booth neighbors said they had paperwork for the show which indicated it ended at 5pm ... and also at 4pm. I told them all I had was an email of the vendor recruitment flyer that gave the hours as 8am to 5pm. They said they'd talked to the promoter (who has a shop in this small Gold Rush ghost town) the previous day, and she had said 4pm was fine. I started gathering my stuff up about 3:30, since I hadn't made a sale in more than 3 hours.
Based on the booth fee, and even the 45 minute drive each way, I did ok. It was just too dang hot ... and the shoppers (what few there were!) retreated indoors when it became unbearably hot.