The best clothing for a hotter environment is a tad counterintuitive, because it's less comfortable in the short term... you want full sleeves, full pants or a long skirt/kilt/toga/whatever (I'm reasonably certain that if heat waves continue cranking it up, these are going to become a unisex thing, whatever we're gonna call them...). You want everything loose so there's room for evaporation to happen (it's your body's natural swamp cooler), you want large openings everywhere so the air can ventilate, and you want lighter colors that reflect. You'll also want to cover your head, preferably withsomething wide (and/or includes the little neck covering flap deal) that creates a lot of shade, but it's currently more common in deserts to see less shade producing scarves/wraps.

You'll feel hotter in the immediate, and overdressed, but you'll overall be absorbing less energy from direct sunlight, and that means a more stable amount of body heat overall, and less risk of things like cancer.

I wear loose t-shirts, jeans, and a wide boonie/fishing hat. Less overall clothing is better, but more coverage is also better. Gotta find that balance is all.

TL:DR, the clothes most people associate with the Middle East... clothes that are worn by people who've dealt with a hotter climate for millennia. The white robe looking getup is what's gonna work best in a hotter climate.

I think one of the questions we need to ask ourselves, more than what to wear, is the sustainability of clothing manufacturing.

What companies make clothes in a sustainable and environmentally friendly way?

My go to has been Patagonia. They do a lot to help with sustainability, the pay better wages than most manufactures, and their reuse/recycle programs are great.

I’ll admit, their products can be expensive so it might not be an option for everyone. However, every piece I own has lasts for years and is very high quality.

• https://www.patagonia.com/one-percent-for-the-planet.html
• https://wornwear.patagonia.com/?utm_source=patww

My plan is to not be alive when it gets bad enough I gotta change my clothing.

Otherwise sunblock and nothing. Out here like greased up deaf guy except with SPF5000

Ladies and gentlemen: The Wife Blazer

Shopping 2nd hand is really the only viable way to get clothes without further impacting biosphere collapse.

Bring back the Speedo

Cooling scarves are amazing. Wide brimmed hat. Shemagh.

pants that zip-off into shorts

https://Goodonyou.eco

Patagonia and thrift/consignment.

A moisture wicking baselayer. Light colored clothing.

Lightweight long sleeve UPF rated sun shirt or hoodie…

A good razor to take off the full-body sweater. Somewhat joking but there's enough good advice here already and I'd be lying if I said some hot days didn't have me reaching for the shaving cream. It's just the thought of the horrible itching during regrowth that holds me back.

How about second hand clothing that makes climate change less likely? We can call that "climate change" clothing also.

Where I live, firefighting gear.

Zip up legs cargo pants/shorts.

Seersucker suits and a good handkerchief. And you should say, “Heavens, it’s warm today.” and sup juleps.