Heat Risk Calculator

One hour without AC on a hot August afternoon can put a 70-year-old in medical danger. Enter your situation and get your heat risk assessment — and exactly what to do about it.

A dim living room on a bright day with the ceiling fan motionless, a thermometer standing on a side table in the foreground and an older woman sitting back on the sofa near a sunlit window

Look at the fan. It is not turning, and that is the whole of it. The power is off, the sky outside is clear and blazing, and the room is quietly climbing while nothing in it appears to be wrong. A house without cooling does not feel dangerous while it is becoming dangerous — which is exactly why the honest answer comes off a thermometer rather than off how you feel.

Enter Your Situation

Answer the questions below. We'll assess your heat risk during a power outage and tell you what actions to take — and how urgently.

1. Age of the most vulnerable person in the home

2. Health conditions (select most applicable)

3. Current medications

4. Outdoor temperature right now (°F)

5. Your home type

6. Do you live alone?

I have read and agree to the Terms of Use and understand the following: The result I receive is a general planning estimate and does not determine whether my home or medication is “safe.” I will not rely on it as medical advice or as a substitute for a licensed physician, pharmacist, or local emergency-management authority. In a medical emergency I will call 911. I agree to the binding arbitration and class-action waiver in the Terms.

What to do right now:

General awareness tool only. This calculator provides a general risk assessment based on CDC and public health guidelines for heat-related illness in older adults. It does not constitute medical advice. Individual risk varies based on many factors not captured here. If you are experiencing symptoms of heat illness — confusion, no sweating, rapid pulse, nausea — call 911 immediately. Consult your physician about how your specific health conditions and medications affect heat tolerance.

Common Questions

Why are seniors at higher risk from heat?

The body's ability to regulate temperature declines with age. Older adults sweat less efficiently, have reduced cardiovascular response to heat, and are more likely to be on medications that further impair heat response. The CDC reports that adults over 65 account for the majority of heat-related deaths in the United States each year.

What medications increase heat risk?

Several common medication categories increase heat risk: diuretics (water pills) increase dehydration*; beta-blockers reduce the heart's ability to increase blood flow to cool the body*; anticholinergics (some bladder medications, older antidepressants, Parkinson's medications) reduce sweating; and antihistamines can also impair sweating. Ask your doctor or pharmacist specifically about your medications.

How hot does a home get without AC in summer?

Without AC, indoor temperatures can rise 10–20°F above outdoor temperatures within a few hours. On a 95°F day with direct sun, an unventilated home can reach 110–115°F indoors. A well-insulated home gains heat more slowly but reaches the same dangerous temperatures if the outage lasts more than a few hours. Mobile homes and poorly insulated structures heat fastest.

What are the warning signs of heat stroke in an older adult?

Heat stroke warning signs include: body temperature above 103°F*, hot and dry skin (not sweating), rapid strong pulse, confusion or slurred speech, unconsciousness or unresponsiveness. Heat stroke is a medical emergency — call 911 immediately. While waiting: move the person to a cool area, cool them with wet cloths or ice packs to the neck, armpits, and groin, and do not give water to an unconscious person.