During a heat wave, the safest strategy is layered: block direct sun, avoid adding heat indoors, ventilate only when outdoor conditions are genuinely better, cool your body, and leave for an air-conditioned place if the home remains dangerously hot. Passive steps and a fan may improve comfort, but they cannot guarantee a safe indoor temperature.
Start by checking the room with a digital indoor thermometer. The Centers for Disease Control and Prevention (CDC) says: “Use fans, but only if indoor temperatures are less than 90°F. In temperatures above 90°F, a fan can increase body temperature.” (CDC, July 20, 2026)
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What to do in the first 30 minutes
- Measure the indoor temperature. Put a thermometer in the room where people spend the most time, away from direct sun, windows, ovens and electronic equipment. Record the reading and check it regularly as the day warms. A thermometer is a decision tool, not a guarantee that a room is safe.
- Block sunlight immediately. Close shades, blinds or drapes on sun-facing windows. Covering windows is recommended by Ready.gov and the U.S. Department of Energy (DOE).
- Stop adding indoor heat. Avoid the oven and limit stovetop cooking during the hottest part of the day. Choose no-cook meals or a meal that can be prepared with a small appliance that does not heat the room as much.
- Decide whether windows should be open. Open them only when outdoor air is cooler and reasonably dry and clean. Close them when outside air is hotter, more humid, smoky or polluted.
- Use a fan only within the safety limit. If the indoor temperature is 90°F or higher, do not rely on a fan for cooling and follow the CDC warning above.
- Cool people, not just the room. Drink water, take a cool shower or bath, and use cool, wet cloths on the skin.
- Make an exit plan. If the temperature keeps rising, identify an air-conditioned public place and arrange transportation before conditions become more difficult.
These actions work best together. None of them guarantees safety during extreme heat, especially for people with medical conditions, people who live alone or anyone who cannot judge symptoms reliably.
Block heat from entering through windows
Use interior coverings during sunlit hours
Direct sunlight turns glass and the surfaces behind it into a heat source. Close blinds, shades or drapes before the sun reaches each window, rather than waiting for the room to become hot. Keep coverings closed on the brightest side of the home while that side is exposed.
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Light-colored or lined coverings can reduce the amount of solar energy reaching the room. The key immediate action is simply to cover the glass; official heat-preparation guidance does not require a particular brand, fabric or window type. Keep a small gap only if needed for a safe window lock or airflow, and do not leave a sun-facing window uncovered because another room feels cooler.
Walk through the home and identify which windows receive morning, midday and afternoon sun. Closing the west-facing windows before afternoon exposure can matter most in some homes, while another layout may heat on the east side first. Treat each window according to its exposure instead of opening or covering every window on a fixed schedule.
Consider exterior shade as a longer-term improvement
Awnings, exterior shades and well-placed shade trees can stop sunlight before it reaches the glass. They are useful home improvements, not emergency replacements for a cooler location during a severe heat event. Check local building, rental and fire-safety rules before installing anything outside.
Renters can still ask a landlord about approved exterior shading or repair of damaged blinds. Do not obstruct a required emergency exit, cover a ventilation opening that must remain clear, or attach a temporary covering in a way that creates a fall or fire hazard.
Open windows only when outside conditions help
Window ventilation is conditional, not a universal heat-wave remedy. It can remove heat when outdoor air is cooler than indoor air, but the benefit depends on temperature, humidity, wind, building layout and air quality. The DOE specifically cautions that ventilation is not an effective cooling strategy in hot, humid climates (DOE Home Cooling).
A practical window decision
- Open windows: outside temperature is lower than the room, humidity is tolerable, and local air quality is acceptable.
- Keep windows closed: outside air is hotter or very humid, wildfire smoke or pollution is present, or opening windows makes the room warmer.
- Recheck later: conditions change quickly around sunrise, afternoon peaks and evening. A window strategy that helped at dawn may hurt by midday.
If you open windows, create a safe cross-breeze only where screens, fall protection and security allow it. Never leave an unsecured opening accessible to children or anyone who could fall.
Do not assume that a breeze automatically means the air will cool the room. If the outside air is hot and humid, moving it indoors may add heat and moisture. Close the opening when the indoor thermometer rises, when air quality worsens, or when anyone in the room begins feeling worse.
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Change cooking methods
Ovens and long-running stovetops release heat into the room. Ready.gov recommends using the oven less during extreme heat. Prepare cold food, cook earlier in the day, or use an outdoor cooking method only where it is legal and safe. Never use a charcoal grill, camp stove or fuel-burning appliance indoors or in an enclosed garage; combustion can produce deadly carbon monoxide.
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- High Accuracy & Quick Refresh Rate: This inside thermometer features a high accuracy of +/-2 to 3%RH and +/-1°F, making it ideal for measuring fluctuating readings like those found in a greenhouse, data measurements are updated every 10 seconds to give you the latest updates on your environment
- High & Low Records: This hygrometer digital thermometer displays high/low temperature and humidity levels to allow you to make proper comparisons using your home’s data
- Healthier Home & Environment: This thermometer hygrometer with temperature and humidity monitor ensures proper indoor humidity that achieves important health benefits for skin and allergen, can also serve as a refrigerator thermometer, freezer thermometer, reptile thermometer, soil thermometer, humidor hygrometer, cigar hygrometer, and more
- Practical Design: This indoor room thermometer features a tabletop stand and a magnetic back, place the temperature monitor on your counter or fridge; °F/°C selector; Includes 1 AAA battery
If cooking is unavoidable, prepare one batch rather than repeatedly heating the kitchen, keep lids on pots where appropriate, and move people away from the hottest room. These choices reduce added heat but do not replace checking the room temperature or planning a cooler destination.
Turn off unnecessary heat sources
Incandescent lamps, gaming computers, televisions, chargers and other electronics all release some heat. Turn off equipment that is not needed, especially in a small bedroom. Do not unplug medical equipment, refrigeration or safety devices that someone depends on. Keep refrigerator and freezer doors closed so they do not have to run longer to recover their temperature.
Concentrate activity in the coolest safe room and close doors to rooms that have accumulated heat, provided this does not block required exits or ventilation. Avoid creating a crowded room, since people and operating equipment also add heat.
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Run dryers, dishwashers and other heat-producing appliances outside the hottest period, if possible. Use the bathroom exhaust fan briefly after a shower to remove moisture, but do not assume it will cool the whole home; exhausting air can also pull hot air in through leaks.
Fans: useful for comfort, unsafe as a sole plan above 90°F
Fans move air across the skin and can make a person feel cooler when indoor temperatures are below 90°F. They do not remove heat from a room unless they are part of a ventilation strategy that sends warmer air outside. A fan can therefore provide comfort without making the space safe.
The CDC’s current guidance is explicit: “Use fans, but only if indoor temperatures are less than 90°F. In temperatures above 90°F, a fan can increase body temperature.” (CDC, About Heat and Your Health, July 20, 2026) Do not use a fan to justify staying in a room that is already at or above that threshold.
Use a fan below the threshold
- Point a fan toward a seated or resting person for short-term comfort.
- If outdoor air is cooler, place a fan near a window to move indoor air out, with another safe opening on the opposite side for replacement air.
- Keep cords away from walkways and water, and stop using a fan with a damaged cord, hot motor or unstable base.
- Do not aim a fan at a person who is already confused, faint, vomiting or unable to drink; seek medical help instead.
Why a fan is not enough
When air is very hot, moving it across the skin may no longer release enough body heat. Humidity further reduces evaporation of sweat. The CDC advises not relying solely on fans during very hot conditions (CDC, Heat and People without Air Conditioning). If the room is approaching or exceeding 90°F, switch from “make it feel better” to “get the person somewhere cooler.”
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- 【Easy to Read at a Glance】 Compact LCD with large, bold digits make temperature and humidity clear at a glance. A 1-hour trend arrow and DRY/OK/WET icons turn readings into simple comfort cues. Switch between °F and °C with one button.
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Cool your body directly
Use water deliberately
Drink more water than usual and do not wait until you feel thirsty, following the CDC’s heat guidance (CDC). Take frequent cool showers or baths. If bathing is not practical, place cool, wet cloths on the neck, armpits and other areas where blood vessels are close to the skin. Re-wet the cloths as they warm.
People with heart, kidney or other conditions that require fluid or salt restrictions should follow their clinician’s instructions rather than forcing large amounts of water. Avoid using alcohol as a cooling strategy; it can worsen dehydration and impair judgment.
Lower exertion and wear for the heat
Rest during the hottest hours. Wear loose, lightweight clothing and use clean, damp fabric on the skin. Move sleeping or resting arrangements to the lowest, coolest room that is safe. Close curtains in rooms that receive afternoon sun even if nobody is using them; stored heat can continue radiating after sunset.
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Plan errands, exercise and physically demanding chores for a cooler period if they cannot be postponed. Keep water and a charged phone within reach, especially for anyone resting alone. Personal cooling can lower discomfort quickly, but it does not make a persistently dangerous room safe for hours.
When to leave home for air conditioning
A home can remain dangerously hot despite covered windows, reduced cooking and careful ventilation. The CDC recommends spending time in an air-conditioned place such as a library, mall or shelter; even a few hours can help (CDC).
Find a destination before you need it
- Check your city, county or state health and emergency-management website for cooling-center locations and opening hours.
- Call local health or emergency-management agencies if online information is unclear. Services and hours vary by place and date.
- Check transportation, accessibility, pet rules and whether the location accepts children or people who need medical support.
- Pack water, medicines, identification, chargers and any mobility or communication equipment.
- Leave while travel is still manageable, rather than waiting until someone is confused, faint or unable to walk safely.
Do not assume a shopping center, library or shelter is open during every heat advisory. Verify the current address and hours locally. If you cannot reach a safe, cool place and the indoor temperature is climbing, call local emergency services for guidance.
Cooling-center information is local and can change during an event. Check weather and air-quality alerts as well as the facility listing. A destination that is technically open may not be suitable if transportation, disability access, medication storage or supervision needs have not been addressed.
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| Measure | Primary effect | Depends on | Electricity | Safety role |
|---|---|---|---|---|
| Shades, blinds or drapes | Blocks incoming solar heat | Window orientation and timing of sunlight | No | Useful heat reduction; not a guarantee of a safe room |
| Window ventilation | Replaces indoor air with outdoor air | Outdoor temperature, humidity, wind and air quality | No, unless a fan is used | Helpful only when outside conditions are better |
| Reduced oven and appliance use | Prevents new indoor heat | Meal and household scheduling | Usually reduces use | Supports other measures |
| Fan below 90°F indoors | Improves perceived cooling and may move air | Indoor temperature and airflow path | Yes | Comfort aid; not a substitute for a cooler place |
| Cool shower, bath or wet cloths | Removes heat from the body | Access to water and a safe bathing setup | No | Direct personal cooling |
| Air-conditioned public location | Moves the person to a cooler environment | Local availability, hours and transportation | Not at your home | Most reliable option when the home stays dangerously hot |
The comparison is about what each measure can do, not a ranking of products. Window coverings and reduced cooking limit incoming or newly generated heat. Ventilation works only when outdoor conditions are favorable. Water cools the person directly. An air-conditioned public location is the clearest escalation when home measures are not enough.
Rank #4
- Face Icon Comfort Indicator: Humidity temperature gauge features face icons to indicate DRY/COMFORT/WET air conditions, quickly informs you how to adjust your humidifier or dehumidifier to achieve optimal comfort
- Highly Accurate Sensors: This temperature humidity sensor features a high accuracy of +/-1°F/°C and +/-2% to 3%RH, making it ideal for measuring dynamic environments like greenhouses
- Fast Refresh Rate: This digital indoor thermometer refreshes every 10 seconds to provide the latest updates for temperature and humidity readings
- Compact Display with Large Digits: This digital thermometer indoor outdoor features a compact LCD display with large bold digits, allowing you to read the room thermometer indoor from any angle and distance
- Multiple Placement Options: This humidistat has 3 placement options - Tabletop Stand / Magnetic Back / Hanging Mount, place the wall thermometer anywhere you wish such as living room, baby room, kitchen, greenhouse, guitar room, office or cellar
Use an indoor temperature plan through the day
Morning
- Measure each frequently used room.
- Open windows only if the outside air is cooler and acceptable.
- Close coverings before direct sun reaches the glass.
- Prepare food and complete heat-producing chores early.
Afternoon peak
- Keep sun-facing coverings closed and windows shut if outside air is hotter or more humid.
- Avoid ovens, dryers and strenuous activity.
- Use a fan only when the indoor reading is below 90°F.
- Drink water regularly and use cool showers or wet cloths.
Evening and overnight
- Recheck the indoor and outdoor temperatures before opening windows.
- Ventilate only when outside conditions are actually cooler and air quality is acceptable.
- Keep a thermometer, water and a charged phone near the sleeping area.
- If the home did not cool after sunset, arrange an air-conditioned location for the next day rather than assuming tomorrow will be safer.
Write down the temperature and time when checking on someone who is vulnerable. A rising reading, worsening symptoms or inability to cool the room is a reason to escalate the plan, not to wait for a preset hour.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Check on people at higher risk
Heat can worsen chronic conditions. The CDC specifically highlights pregnancy, asthma in children or teenagers, heart conditions and other chronic medical problems (CDC). Check on relatives, friends and neighbors, especially anyone who lives alone or has a chronic condition.
Do not rely on a text message alone if someone may be confused or unwell. Visit safely, call another contact or request a welfare check when appropriate. Confirm that the person has water, a working thermometer, a transportation plan and a cooler destination.
People who live alone may not notice gradual overheating or may delay asking for help. Agree in advance on check-in times and a backup contact. Children, older adults, pregnant people and people with chronic disease may need an earlier move to a cooler place, even when they initially say they feel fine.
Recognize heat illness and get help
Symptoms that need prompt medical attention
Muscle cramps, headache, nausea or vomiting can be signs of heat-related illness. The CDC advises seeking medical care immediately for these symptoms (CDC). Move the person to a cooler environment, loosen excess clothing, offer small sips of water only if they are awake and able to swallow, and apply cool, wet cloths.
Suspected heat stroke is an emergency
Confusion, loss of consciousness, seizures, very hot skin or inability to drink can indicate heat stroke. The National Weather Service describes heat stroke as an emergency requiring immediate 911 or hospital care (NWS Albuquerque, Excessive Heat). Call emergency services, move the person to a cooler place if you can do so safely, and cool them with wet cloths while waiting. Do not delay the call to search for a better home remedy.
Do not leave a confused or unconscious person alone, and do not make them walk to a cooling center. Tell emergency dispatch the person’s symptoms, location and whether they are conscious and breathing. Keep monitoring them while following dispatcher instructions.
Prepare before the next heat wave
- Keep a digital indoor thermometer where you can read it quickly.
- Repair or improve shades and identify the windows that receive afternoon sun.
- Store clean washcloths, drinking water and lightweight clothing together.
- Write down nearby air-conditioned public places and their verified hours.
- Arrange check-ins with people who live alone or have medical vulnerabilities.
- Learn your local heat-alert and air-quality information sources.
These preparations reduce delay, but they do not change the safety boundary: if the home remains very hot, especially at or above 90°F indoors, use a cooler location and seek medical help for symptoms.
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- Real-Time Precision Monitoring with High Accuracy Sensors: Built with high-precision sensors, this indoor thermometer hygrometer delivers real-time temperature and humidity monitoring with reliable accuracy. It features a wide measuring range from -58°F to 158°F (±1.8°F accuracy) and 10%–99% RH humidity range (±5% RH accuracy). Providing stable data for daily home monitoring.
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- Intelligent Auto-Calibration & 5s Fast Data Refresh: Featuring automatic calibration technology, this thermo-hygrometer starts a 3-minute precise auto-calibration after power on. The flashing temperature and humidity readings during operation indicate calibration is in progress. It updates temperature and humidity data every 5 seconds to capture real-time condition changes.
- Ready to Use Out of Box: This user-friendly digital room thermometer comes with a pre-installed AAA battery, supporting direct out-of-the-box use without complex setup. It allows one-click seamless switching between ℉and ℃ units to adapt to different reading habits and regional needs. (Note: The power and ℉/℃ switch is controlled by one single button located on the back of the unit. Short press to turn on the device, and press again to switch between ℉ and ℃.) The complete package includes 1× thermometer hygrometer and 1× AAA battery, saving you the hassle of extra installation.
Frequently Asked Questions
How can I cool my house without AC during a heat wave?
Close shades, blinds or drapes on sunny windows; avoid ovens, dryers and other heat-producing appliances; open windows only when outdoor air is cooler, less humid and clean; and cool your body with water, cool showers or wet cloths. If the home remains dangerously hot, spend time in an air-conditioned public place.
Should I open windows when it is hotter outside?
No. Keep windows closed when outdoor air is hotter or very humid, when smoke or pollution is present, or when opening them raises the indoor temperature. Recheck conditions later because the best strategy can change from morning to afternoon or evening.
Do fans help when the room is over 90°F?
CDC guidance says to use fans indoors only when temperatures are below 90°F. Above 90°F, a fan can increase body temperature, so do not rely on one as your cooling plan. Move to a cooler, air-conditioned location when needed.
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What is the fastest way to cool a person without air conditioning?
Move the person to the coolest available place, offer water if they are awake and able to swallow, use a cool shower or bath, and apply cool, wet cloths. If there is confusion, fainting, seizures, very hot skin or inability to drink, call 911 or local emergency services immediately.
Where can I go if my home is too hot?
The CDC suggests air-conditioned places such as a library, mall or shelter. Check your city, county or state health and emergency-management agencies for cooling centers, current hours, transportation and accessibility. Verify details locally because services vary by place and date.
Who should I check on during extreme heat?
Check family, friends and neighbors, especially people who live alone or have pregnancy, childhood asthma, heart disease or other chronic medical conditions. Confirm that they have water, a thermometer, a way to travel and a cooler destination.
Is a digital indoor thermometer worth having?
A digital indoor thermometer is a practical way to track the room temperature and apply the CDC’s 90°F fan-use guidance. It measures conditions but does not cool the room or prevent heat illness, so pair it with a plan to cool the person or leave.
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The Bottom Line
Cover sunny windows, avoid making heat indoors, and open windows only when outdoor conditions are cooler and cleaner. Use fans only below 90°F indoors, cool your body with water, and leave for an air-conditioned place if your home stays dangerously hot. Headache, nausea, vomiting, confusion, fainting or other heat-illness symptoms require prompt medical attention; suspected heat stroke requires emergency help.
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