Around here, you should probably carry an umbrella not only when it's pouring rain but also when it's burning hot.
Ancient apartment buildings = No central air.
No central air = Air conditioners in every third window.
Walking to and from the subway stop four blocks away, I see many a sidewalk puddle on a 90-degree day. That means watch your step. Walk through the puddle and your head will probably feel a few drops of condensation from the air conditioner above.
New York experienced another heat wave last weekend, so the a/c was obviously in high demand. Early Sunday morning someone with a loudspeaker drove through the streets asking everyone to turn off all non-essential electrical appliances because of a power outage in the neighborhood. Luckily it didn't affect us.
And my air conditioner is essential. We didn't turn it off.