Grew up in the southern US and just spent a couple weeks in the Philippines:

• cold drinks
• fans
• lightweight, breathable clothing

That's about it - the sweat is unavoidable

I used to live in Mexicali where IIRC we reached 53C one summer for a few days, the rest were max 50C for a couple of days (during the time I lived there), there was no rain, no clouds, and little to no wind.
I had an office job, so only my commute had me outside during the day, maybe also going to buy lunch.
For the most part it was only to go out after the sun had set if I wanted to do something. All the stores, houses, and businesses have AC, also the public transit even if it just mildly lowered the temperature.
I heard stories that before AC people just endured it, sitting outside at the shadows of few trees and other kind of covers.
Also the original settlers made an underground city to endure the heat.
IIRC the first mall that had AC (La cachanilla) was so popular that during summer it was common to be incredibly full, the verb "cachanillear" was used to mean to go walk in the mall, mostly just during the summer.

Now in Montreal the heat is very humid and I miss the dry heat of the dessert haha.
In here the houses are built to trap heat for the winter, but it backfires during the summer.
Again, with an office job, and now fully remote thanks to the pandemic, a portable AC does the trick.

Also, I don't remember where I read it, but simple fans stop being useful after certain temperature, but I don't remember what it was.

Keep house dark. We cook outdoors in summer on BBQ or using solar oven. Ceiling fans only. Keep out of the sun and grow trees that provide shade for house.

I live in Chihuahua, Mexico, where it usually means dry heat so pretty much anything works but it also means you can use a thing called swamp coolers that pretty much just increase humidity by humidifying air and shooting it quickly. They are incredibly efficient.

Sad part is when it gets humid (in monsoon times) it really doesn't sufice, so an AC is required or just remove as much clothing as possible.

Clothing does help a lot with dry heat, you can use thin fast-drying clothing and that helps evaporate sweat which takes away most heat. Again in humid heat you really can't cool unless you dehumidify with an AC (which is incredibly efficient the more humid the area is, and can be inverted to be used as heaters for much cheaper than gas or normal resistive electric heaters).

In the UK I think your best bet is a reversible heat pump.

If you are or were a student in Australia, Mexico, southern USA, Spain, Portugal, Greece, South Africa, or any other hot parts of the world, how do/did you stay cool during the day?

I live offgrid in a campervan in the desert US. I maintain temps by snowbirding (changing elevation and latitude to follow mild wx).

I have shadecloth and an evaporative cooler when things get a little intense. Temp-controlled roof vent.

I'm from southern Spain, the most important thing to do here is to stay in the shade, otherwise you risk a heatstroke. If indoors usually I manage with a fan as close as possible, but sometimes I need to turn the AC on. Honestly the worst part of it is the sweat, your clothes get soaked and you get stuck to the chair lol

Sweat is kind of unavoidable (especially where I live where it gets very humid). Cold beverages (drink plenty of water), stay in the shade, jump in a pool (not an option for everyone, sometimes ill just splash cold water on my face), AC is wonderful (also not an option for everyone), or at least turn on some fans and get some airflow on you.

Pretty much what other users said:

• remember to drink (water is the best but if you feel fatigued from the heat there are supplements that you can add to the water, ask your pharmacist)
• natural fibers clothes like cotton or linen are better that synthetic ones
• you can even buy a little fan to put on your desk, they’re powered through a usb so you don’t need a socket, just your pc
• if you’re outside in the sun don’t forget a hat
• eat a lot of fruit and vegetables, they’re fresh and have all the good vitamins and plenty of water Hope this helps! From the sunny Italy

From my experience in the UK, it is quite humid, went to Liverpool and London last year. I'm from central america, in a city that gets humid and getting increasingly hotter by the year.

Hot and humid means there's really nothing you can do to cool down other than let yourself sweat and try and catch a breeze. Buy yourself a nice pair of shorts above the knee made out of a breathable fabric (100% cotton, cotton/linen mix, etc., avoid plastic and sports fabrics, they trap heat and moisture) and some shirts made out of the same material. Keep yourself to the shade, use sunblock, and stock up on cold beverages and/or fruit to make beverages with.

If summers in the UK somehow are dry, covering yourself head to toe with breathable fabric will do the trick. There's a reason why arabs wear drapey clothing.

Mind you, sweating above 36-37 in a humid environment does nothing, as the humid air and heat makes it impossible for your body to transfer heat out. Really sucks y'all can't get ACs up there. I dunno what I would do w/o one. I'm not made for temps above 25 and I can't sleep on a moist mattress.

A fan with a damp (cold) cloth on it.

Fans, and a general preference for being hot and sweaty over wearing thick/multiple layers of clothing to avoid the cold

I don't live in a hot place, but I am learning to cope with higher temperatures, and these are a few tips:

• Wear garments in cool fabrics, like Linen

Linen is one of the better types of garment to keep cool during summer. For a sunny day, long linen pants and a long-sleeved linen shirt will help you beat the heat in the sun. I find that linen helps with the issue of perspiration, as it does not retain moisture in the same way that cotton and some synthetics do. It's also a pretty decent choice from an environmental perspective.

• Use fans to reduce perceived temperature

Wind helps keep body temperature low by aiding in the effectiveness of perspiration, i.e. sweat evaporating and reducing body temperature. This will only be effective if your indoor humidity is not too high, see later tips on that topic.

• Keep the sun away from the building

If you can shade the building you are in, it will heat up less. Awnings can be useful in this regard.

• Create a draft when the outside temperature is lower than the inside

This relies on the layout of your building being appropriate, but try to keep windows open at times when it's possible. Bug nets can be useful to keep things open without getting unwanted guests.

• Keep things closed when the outdoor temperature is higher than indoors

You'll want to try to maintain the amount of cool air as much as possible. Manage the climate actively, best as you can.

• Turn off things that generate heat

This relies on things like you not working from home and having to keep a computer on, but even under those circumstances, you can still try to switch from high energy devices to lower energy devices (stationary computers vs laptops, TVs vs phones). Higher electricity consumption is generally going to mean higher heat generation.

• Drink lots of water

You'll need it to maintain good hydration, which keeps perspiration working, which is fundamentally what's going to keep you cool when temperatures are hotter than what keeps you optimally cool.

• Go for a swim

If you have access to even mildly cool water, this can help refresh you when you're feeling the heat. It's also fun.

• Buy an AC

At the end of the day, perceived temperature can be a pretty hard factor to manage. When you've exhausted the rest of the list, you may need to get an AC, which will both cool the air and reduce humidity, which in turn decreases perceived temperature and generally increases comfort. If you can get one installed, that's ideal, but if your country is anything like mine, you might be stuck with a portable one, which is unfortunately pretty inefficient. Try to get a good seal on the outdoor-part of the AC unit to help it work as efficiently as possible.

Lived in hot parts of the states and Canada. Pretty much just stay hydrated and take cooloff breaks when possible (whether AC, or cold showers.) Inside, use reflective or white materials to block windows to reflect sunlight out - blackout curtains are fantastic for this. Become a goblin - the sun is your enemy indoors when it comes to super hot days, especially if you do not have AC.

Also, do hot activities outside. Ie, BBQ all the things and don't run the stove or oven if possible.

Not much you can do about sweat. Just be sure to dry out your clothes every here and there so you don't have moist clothes on 24/7, or you could end up with a fungal skin infection (in folds if you have any, or the more private areas.)

Southern US here, my household acclimatized. Last year we didn't run the AC until the last week of July and we cut it back off at the end of August.

First thing in the morning we open all the windows, put fans in the Western windows, and open the attic door. Cooler air is pulled in from the South West, convection pulls hot air to meet it, and then the hot air rises out of the living space. It's still hot, we sweat all day, but you become accustomed to it and shift your life around it. We get up early, do any chores before lunch, rest from noon til late afternoon, do other activities in the evening. Sweat helps cool the body, if you sweat you'll be cooler, but you have to stay hydrated.

A wet towel on your neck and shoulders can really help out, they make stretchy ones that are really nice, plus they help keep the sun off your neck

Run cool water over your forearms.

If you have a bucket of ice water you can dunk your arms in for extra effect.

Helps cool you down pretty quick.

not from a super hot place, but we do get up to like 35-40 degrees in the summer at times

best way to cool is to open windows at night, close them and the blinds during the day, submerge yourself in water for additional cooling :)

Cool bath at the worst of the heat. Cold drinks.

Hi, I'm from Rio de Janeiro, what I usually do is to keep a big bottle of water always by my side, I try to drink at least 3L each day. I also like to have a fan pointing directly at me when it's too hot. Light clothes also help a lot, try sleeveless shirts and bermuda shorts if you can

Have you tried using a neck gaiter?

Ex: Buff neck gaiters

Time also helps. The longer and more you spend in the heat, the more you get used to it. Your body will adapt.

I come from the cold north and live in a tropical area now. The heat used to kill me. It still does 15y later, but I can handle it much better than before.

If you don't have AC, fans, cold drinks, and trying to move as little as possible. The moving thing isn't the worst, kids run around all summer, but it's mostly because in the southern US we have lots of water to spare to just hose ourselves off. It doesn't have to specifically be cold, but water coming from the ground is cool, and it works like sweat in that any breeze coming in will feel so much cooler. You can wear little and skin exposed clothing, but this can also make you burn. Mostly just stick to light and breathable fabrics. Skirts are super nice.