When I lived without air-conditioning (from birth to 2013), I always closed curtains and windows during the day and opened up at night. (All properly kept Canadian homes have fly screens, and this is why.) An electric fan oriented to blow across the bed makes the steamiest night tolerable.

Showers were taken at night just before going to bed, and one never towelled oneself completely dry. While still damp, sprawl on the bed in the breeze from the fan … Aaaah!

Old houses are easier to live in without air-conditioning as they are designed for cross-ventilation. Modern (post-2000) houses — not so much.

Most important, dress suitably for hot weather, in loose cotton clothes you can sweat through without regret. Jeans are usually both too snug and too heavy, contributing to heat rash in the crotch and around the waist.