Think of people you know who may be more susceptible to heat and check in with them often, especially in the evening when indoor temperatures are highest. If you cannot check in-person, ask them to tell you what it says on their thermostat or indoor thermometer.
Encourage those who may not know they are at higher risk to take cool baths, sleep in the coolest room, or stay with friends.
If your home is cooler, invite those who are at highest risk to stay with you.
Never leave children, dependent adults, or pets alone in a parked car, leaving windows open will not help.