Update: I bought the cheap boonie hat from Dollar General. So far I'm glad I've only spent $5 for it. I ended up having to wear it at lunch. Conditions were sunny, with temperatures just at 90° F/ 32° C. Assessment: It retains heat more than I anticipated. It was particularly noticeable around the brim right about my ears, which was unusual. I had worn my straw lifeguard /farmer's hat just a few minutes earlier, and the difference was quite noticeable. The straw hat was cooler. I'd have have one of my Panamas to compare it to, but I think they would be cooler than this thing. A pity: It's well made, though I suspect it's a factory second. One of the vent holes is placed slightly off, but they're screened, and it has a thin inner liner. I need to find somewhere I can actually try a Tilley hat. The LTM2 looks the most promising, but I'm reluctant to put down that much money for something I can't try on first. Another alternative: A thin, tight-weaved, Western style straw hat with vent holes. This I should be able to find at a local feed store, or, failing that, maybe Tractor Supply. I'm quite serious about Tractor Supply. If you're into Western style hats, they can be a surprising source. Also serious about the local feed store. I bought my life guard /farmer straw hat at one, and it looks much better than the last Walmart had on sale. The last alternative is the French style pith helmet. Unfortunately, I just don't see wearing something like that to town. OTOH, I'm not too comfortable wearing this boonie hat in the same situation.