Most people deal with heat waves by staying in air conditioning. This works pretty well, except you have to stay inside and all that electricity gets expensive. For 14 years I lived in regions with triple digit heat and had to manage my electricity costs. Right now I'm living in a milder climate but with an air conditioner that does not really work. I've adopted a few techniques for staying comfortable without ending up with a $500 power bill.
Buy some fans. Get both box fans and oscillating fans. They certainly aren't air conditioners but they will help a lot.
How to use fans effectively:
How you use a fan to cool off depends on the time of day and your situation. When it is roasting hot out and heat is surging in an open window, it can be better to shut your windows. Or, you can leave them open a little for ventilation. Also, windows on the north side or the shady side of a house can be left open because the air should be a little cooler there. Now set up your fans throughout your house to keep air moving.
Venting heat out of windows is very important. This is where you can use a box fan or those smaller fans meant to fit into windows. Set the fan in the window and direct its airflow out. This is especially important in upper levels where heat can build up dangerously.
Once night comes and the air cools off a little, you can cool your house down significantly by putting some fans in windows blowing out and other fans in other windows blowing in. This will vent the house and draw in the cooling air of the night.
If you do this all night, your house will actually be pretty comfortable come morning. Then you will monitor the heat rise for the new day and shut some windows and draw curtains to keep out the rising temperatures.
Sleeping in the heat without air conditioning
Oh the challenge of sleeping in the heat. This is where the crabbiness of sleep deprivation meets the fussiness of prolonged sweatiness. My preferred thing to do is set up an oscillating fan (they tend to be quiet) so that it breezes across my bed. Then I get a wet rag and use it like I have a fever. I cool my forehead, neck, chest, core, and feet. Holding the wet rag over the massive blood flow going through the neck is particularly effective for drawing the heat out of your body. The rag leaves wetness on your skin that will evaporate heat off your body. This gives your body a cooling boost beyond what it can achieve with sweating. And the fan breezing across your skin will accelerate the evaporation and pull out more heat. With this technique I often fall sound asleep within 10 or 20 minutes. Of course you'll need to sleep naked or nearly naked to use this method, but it's a heat wave so what are you doing wearing clothes to bed anyway?
If the night is actually cooling off you can put the fan in the window to blow on you in bed instead of the oscillating fan inside the room.
Another technique for sleeping in a heat wave is to sleep outside. If you have a screened in porch, sleep out there. I occasionally fall asleep on the couch on my screened in porch if it's really hot and muggy. Also if you have a tent, set it up. The cool ground and the outdoors are better than a stuffy bedroom.
Dealing with the heat when you're working outside
You will need to be careful about working outside in the heat. You really have to self monitor and make sure you don't overheat. Step one is (for heaven's sake) put on a hat. The bigger and broader the brim the better. A good, light colored straw hat with a wide brim is an absolute necessity in my book. I swear it's ten degrees cooler under there.
Next, soak a bandana with cool water and tie it around your neck, just like the people in old cowboy movies. The wet rag around the neck helps draw the heat out of the blood moving through your major neck artery and vein. Admittedly this works best in dry heat. Hot humid muggy heat really decreases the evaporation but you'll still get some help, so do it.
Work in short spurts. If some bust ass jobs are necessary out in the bad heat, then take lots of breaks to cool off. Drink cold drinks and keep refreshing your neck rag with cool water. A loose long sleeve shirt to keep the sun off your upper body can help too. If you want to wear no sleeves or no shirt, put on sunscreen. This helps keep the sun's heat from frying into your skin. My skin with sunscreen on it feels cooler than skin without sunscreen.
Use your basement to stay cool
If you're fortunate enough to have a basement, especially a finished basement, then definitely go down there to cool off. (I'm chilling in my basement as I write this.) It is a naturally cooler space because it is insulated by the Earth and has a substantial structure over it to protect it from the blistering heat wave. Taking breaks from the heat in the basement will help you find some relief from the heat.
Cooling centers help people without air conditioning
Sometimes you just need to get into some air conditioning even if you don't have it or can't afford to use it at home. During bad heat waves, find out if any cooling centers have been opened in your town. Even if there are no official cooling centers, you can always go to the grocery store and spend a LONG time shopping for Popsicles. Another free place to relax in a cooled environment is your local library. This is a public space and quiet people can hang out for hours and read magazines and books. Often you can spend some time on the internet as well.
If you can afford a movie ticket, go to the movies. It's been a wonderful place to cool off for decades. This is how a crappy movie achieves blockbuster status during a big heat. People just need some chill time no matter how many car explosions they have to view.
Put on your bathing suit and start splashing
If you can enjoy a water source, then go for it. Also there's no law against an adult running through a sprinkler, but I suppose that it will help you look normal if you have kids in your household.
I hope that my tips for cooling off during a heat wave even if you don't have an air conditioner will be helpful to you.
Tracy Falbe writes fantasy novels available at Brave Luck Books where strong characters take chances.