If you have space outside, plant native trees/vines/bushes that will help shade the building from the sun if you’re getting direct sunlight. You can just do clippings from wild growing plants for free.

timing of the windows opening and closing is key. Also tracking temperature helps, just a crappy thermometer (one indoors and one outside not in sunlight) will let you know when it’s time to open or close up.

Concrete/bricks work both ways as a thermal mass, if you can get them cool and covered from the sun it will help cool your area (think of cold concrete floors, I have an inner brick wall that an extension was built out on and it stays coolish). Same with water, most have experienced a cold water pool/pond on a hot day, big blocks of frozen ice can do the trick if you stick to freezing at night.

Free stuff:

• No/less electronics during the day (tvs/chargers/computer), it all adds to the heat
• no cooking during day, cold cuts/food only till night
• Take a nap during the hottest part if possible, or just sleep in daytime and move about at night on off days (something about waking up after a nap makes it seem less overbearing)
• do maintenance on your fans, take them apart and clean/grease anything that needs it (will need to clean more often if you lubricate due to dust build up causing gunk)

Black-out curtains are great to stop light, but if it’s entering the window already it’s just heating up that one spot so you’re still technically getting the thermal radiation. For that fix you would want reflective window covers, even foil would technically help slapped to the window (it’s the only time those reflective insulation boards actually do anything with infrared). Foil with something behind it to insulate, like literally anything (cardboard wrapped in plastic to air seal can even do it), then you can take down your contraption at night to let air through to cool.

Insulating and air sealing. Alternatively, air flow in any spots building more heat than the outside temp (like an attic or upstairs area). If it’s a family owned place it’s easier, renting you might have to address concerns with landlord.

Currently temps in my area are getting about 95f(35c) daytime and 65f(18c) to 60f(15c) at night. I can usually get my house down to 68ish(20c) before the sun comes up. Windows in a bottom floor with fans pointing in, any windows upstairs with fans blowing out (hot air rises, it’s the same technique for american colonial/victorian houses with dormers emulating ancient style architecture for passive cooling). If it’s single story just be aware of wind direction if you’re using the fan method and point some in where the wind is blowing and pointing out at the opposite side. My house will at max hit about 80f(26c) but by then it’s time to open the windows because the sun has set.

At some point, once true-true summer hits, the nights will be about 80f(26c) and over 100f(38cish) during the day. At that point regulating your body and getting used to the temps is key and an A/C or sometype of ground thermal air flow is the only way you’re going to make anything cool. If you’re using A/C just seal the crap out of your windows with plastic and/or insulation (remember condensation like an ice cup though will cause moisture and mold/mildew growth on the exterior if not done properly). Pick a room that keeps the coldest and put whatever you can on the walls and windows (even a quilt on the walls will help insulate some). Seal up as much as possible and hide from the heat.

I grew up without AC. Midwest U.S. Very hot. Very humid.

Sleep naked. Sleep on cotton sheets. Not synthetic.

Open all the windows at night. Close them up by 8 or 9 am.

And fans.

Don’t underestimate what a fan can do.

You can mimic the cooling effects of sweating by misting yourself with water or jumping in the shower for 5 min and then putting a fan on.

Wet hair always helped me cool down. especially with a fan on.

We used fans a lot growing up and I use them at home now with AC. I can be comfortable at 76-78 with a fan on.

No fan, and I need 71-72.

So it’s a way to save on electricity.

Also I wear less clothes. That always helps. Avoid socks. Tight underwear.

If you are a woman, I suggest switching to boxers when you are home.

Men’s boxers are better than “women’s” boxers. Which are just expensive boyshort underwear.

You need a loose crotch area.

Just buy mens in packs. Less expensive too.

Drinking super cold water often also helps.

What I do. I have 2 water bottles. I fill them half full and put them in the freezer. I take one out at a time. Fill with water. Have ice cold water for a long time since it’s not cubed. Then when it’s no longer icey cold. Switch it out for the other.

I would do this at work. Just write your name on the bottle and tell others not to throw them out, that you reuse the same one. Otherwise someone cleaning might think the same bottle has been in there for a month and decide to toss it out.

Can’t live without AC in Mumbai…

I grew up here in Florida without air conditioning until I was about 25.

Really just learned to be still, that helps. Keep the windows open at night if it cools off at night.

Stay in the shade, if there is a breeze it is not bad. Fans, fans, fans. Carry a parasol if possible . Shade helps so much.

And I wait for the rainy season, ours is at the same time of year yours is. Love that time, every day it gets hot but then in the afternoon the rain comes.

ETA I think India has this covered already but stay away from synthetic fabric and cotton. Linen or silk are best, and oddly, light merino wool in a loose fit is also so good in the hot weather.

I live in the American Southeast. We generally turn on the air conditioning.

So, a lot of this is duplicated, but it’s a list of what I do against the heat …

External shutters outside of the windows, both are closed the moment the sun hits to shut in the cold(er) air, and open over night. We also have tiled shades over all the windows so there’s no direct sunlight into the house during most of the day.

Ceiling fans running at low speed

Cold 2 minute showers in the middle of the day

Put on a cold wet t-shirt

Wear as little clothing as possible while out of the sun. In the sun, light coloured breathable loose material (linen trousers are a godsend against mosquitoes)

Don’t go outside or be active in the hottest part of the day

Don’t eat much, if at all, during the day

And my wife’s favourite - getting in a kid’s paddling pool (I don’t like it, but she does)

Whrere I live, temps go in the 40-50°C range in the summer (and 60+ in some inland areas). Here is what we do to stay cool.

1. Cool(er) air ventilation Windows open at night, closed past morning, with blinds down when sunlight starts hitting the windows. Ensure that air can circulate through (otherwise, you might actually get heatstroke from how hot the house gets). In cass the heat makes you feel like you cannot breathe, blinds down and windows open (better than suffocating) Also, no joke, get greenhouse green screens, and set them up inverse outside your windows. Instead of trapping heat in, they throw heat out instead. Surprisingly cooling.

2. WATER AND COOLING FOOD! Water is a must, and there are foods that cool you down instead of warming you up. (avoid the later wherever possible!) Examples of cool foods: frozen desserts, lassi (yoghurt water drink, makes you sleepy) etc

3. Fans. Fans everywhere. Doesn’t matter if hot enough that it feels like a hair dryer instead. Evaporation + air is your friend (bonus tip: if you live in a dry zone, get an air cooler. It’s an enclosed fan behind a self contained waterfall. Humid air is particularly cooling. Beware metal cabinets in the same room though. They rust, bad).

4. Baths. Baths are especially cooling. Take at least 2 a day. My cousins, who live inland at 60+ temps, bathes at least 4-5 times a day. Also, their bathrooms all have massive fans :)

5. Clothes. In summer, we wear our thinnest, oldest cotton clothes possible (aka, almost seethrough). We never go out in them, but they sure make the house bearable.

6. Naps and talcum powder. Human body temps naturally decrease when napping. Talcum powder, spread on the hottest parts of the body, absorbs heat and cools you too. The powder gets soaked in sweat and is useless pretty quickly, but combine bath + fan + powder + nap (and probably no undergarments/naked) makes noon bearable to go through. Talcum powder in particular stops rashes from too much sweating, if you have trouble bathing more than twice a day like I do.

Thats about it from me. Hope it helps!

Using IR blocking films (like the ones that they use to tint car windows, preferably the type that use static cling instead of adhesive because they’re far easier to apply) on any windows helps to keep the incoming heat down during the day,

Having airflow through the house at night with open windows or some form of vent, just make sure to add in bug nets to block any intrusive animals.

The addition of louvres (solid panels that have angled plates in them to block sunlightbut allow airflow) to the outside of windows can help keep temperatures down as well.

Things me or my parents would do those 40⁰C+ days:

Pull down the blinds to block the sun during the day. If the air is considerably hotter outside, don’t open the windows/doors. Wait until there is no difference in temp to do so.

If access to water isn’t an issue, once the sun goes down you can hose the exterior of the house, walls and any surrounding concrete/stone surfaces. It will cool it down considerably.

If it is really hot I would sometimes put a wet towel on wherever I was feeling the heat the most (usually heads and shoulders/arms). You will need to soak it every hour or so, because it will start to dry and warm up as you wear it. You can sleep like this, too, but you may wake up from the heat under a hot towel that’s nearly dry.

stay inside naked

Lie under a damp towel with a fan on the towel for evaporative cooling.

A/C is great if you can get it.

This isn’t going to be an option very often, but when the conditions are just right I like to leave windows open overnight to cool down the house. If it’s going to be below 60°F and above 80°F the next day, it works best for me. Keep an eye on the dew point though because too much humidity isn’t great. I like to open windows on one side of the house then open another in the other side with a powerful pedestal fan sitting about 4 feet away. That seems to work best for moving air through the house and usually lets me get away without running the AC the next day. Also, Vornado makes a transom window fan that fits snuggly in the window case, that’s a great balance between blocking out a bit more noise because the window isn’t wide open, it’s a noise machine, and a huge benefit is it’s reversible.

Good luck!

Try bamboo sheets. They are a bit expensive but they feel cooling in the summer, they are very breathable but are also have a weight to them to help you sleep.

In tropical countries I carry an umbrella everywhere. It’s much better than a hat because it has more airflow and provides more shade.

My area isn’t the hottest, but it does usually get up to about 100F for a day or two most years, and in the summer temps are in the 80s or 90s during the day pretty consistently, and it can be humid.

I have a mostly finished basement, I’ll spend a lot of time down there over the summer, it stays pretty consistently cool.

I’m lucky that I work night shift, so it’s easier for me to do stuff in the evenings or early morning before it gets too hot.

There’s a saying that there’s no such thing as bad weather, only inappropriate gear. I usually joke that in the summer that means air conditioning.

But if you don’t have a/c, opening your windows and getting some fans going can really go a long way to keeping your house cool.

Limit your time outside, find somewhere to sit down in the shade and take a break if you need to.

Dress appropriately for the weather, lightweight, light colored, breathable clothing, linen is great if you can find it. Maybe consider wearing a wide-brimmed hat to keep the sun off your face and neck when you go outside.

Drink lots of water, find some cool foods to eat, watermelon, cold soba, ice cream etc.