Heat Advisory & Excessive Heat Warning

The National Weather Service issues heat alerts from local offices that calibrate thresholds to what’s normal in your region. A 95°F day triggers an advisory in Maine; the same temperature in Phoenix doesn’t rate a mention. What the labels mean — and what you should do — stays the same regardless of the temperature number that triggers them.

These are the questions people search most during heat events — with straight answers that don’t require a meteorology degree to understand.

• 1
  What is a heat advisory in the US? A moderate-level heat alert from the National Weather Service · Heat index typically exceeds 105°F in most areas · Dangerous but not yet at the warning threshold · Issued within 12 hours of onset

  A Heat Advisory is the National Weather Service’s way of saying: dangerous heat is happening right now, and if you are vulnerable — older, very young, ill, or without air conditioning — you need to act. It’s the lowest of the three heat alert categories but should not be dismissed. The heat index (a combination of temperature and humidity that reflects what the air actually feels like on your body) is the key number, not the raw temperature. At a heat index of 105°F, heat cramps and heat exhaustion become real risks after even moderate activity. The NWS issues an advisory within 12 hours of when conditions are expected to begin — so when you see one, the dangerous heat has already arrived or is imminent. Check your local forecast at weather.gov every morning during warm weather months, not just when you already feel hot.
• 2
  What is the difference between a heat advisory and a warning? Heat Advisory = dangerous but not extreme · Excessive Heat Warning = life-threatening conditions for everyone, not just vulnerable groups · Warning requires immediate action, not just caution

  The most important distinction: a Heat Advisory calls for extra caution and protective steps, while an Excessive Heat Warning is the NWS telling you in plain language that people can and will die without immediate protective action. An advisory is issued when heat index values are expected to hit roughly 105°F. A warning fires when conditions reach 110°F or above — and in some regions, that threshold is even higher before a warning is triggered. The NWS website for excessive heat warnings states directly: “if you don’t take precautions immediately when conditions are extreme, you may become seriously ill or even die.” That is unusually blunt language for a federal agency, and it’s used deliberately. A warning means your air conditioner is not a luxury item for the afternoon — it is medical equipment.
• 3
  Where is it hot in the US right now — which states are under heat alerts? Check heat.gov or weather.gov for live, real-time alert maps · Recent heat waves hit Texas, Missouri, Kansas, Iowa, Arkansas, Tennessee, and the entire East Coast · NWS HeatRisk tool shows your county’s 7-day heat danger forecast

  Heat alerts shift constantly — sometimes by the hour during an active event. The fastest way to see exactly which states and counties are currently under any form of heat advisory, watch, or warning is to visit heat.gov, which is run by NOAA and the federal government and updates in real time. Weather.gov lets you enter your specific zip code to see active alerts for your exact location, including the precise heat index forecast for the coming hours. The NWS’s HeatRisk tool at wpc.ncep.noaa.gov/heatrisk shows a color-coded, county-level map of heat risk up to seven days in advance — rated from 0 (no risk) to 4 (extreme risk). This is the same tool emergency managers use to prepare cooling center activations. During the most recent major heat event, the NWS posted that a widespread heat wave was building across the central U.S. before shifting to the East Coast, where the highest temperatures came a few days later.
• 4
  Why is it so hot in New York City right now? Urban heat island effect traps heat · Dense concrete and asphalt absorb and radiate heat · Less green space than rural areas · Heat index in NYC has approached 115°F during recent heat events — rivaling Death Valley readings on those days

  Cities like New York, Chicago, and Houston trap heat differently than rural areas because concrete, asphalt, and buildings absorb solar radiation all day and release it slowly at night — preventing the cooling that would otherwise happen after sunset. This “urban heat island” effect can make a city 10 to 20 degrees warmer than surrounding suburbs during a heat wave. During a recent major event, heat index values in New York City and Washington, D.C., were compared to Death Valley — a statistic that sounds impossible but reflects how dangerously the combination of high temperature and high humidity distorts what the air actually feels like to a human body. Upper-floor apartment dwellers without air conditioning, residents of neighborhoods with little tree canopy, and people in poorly ventilated buildings face the highest urban heat risk.
• 5
  What are the symptoms of heat exhaustion vs. heat stroke? Heat exhaustion: heavy sweating, pale clammy skin, dizziness, nausea, weakness · Heat stroke: HOT DRY skin (no sweating), confusion, body temperature above 103°F — call 911 immediately · The shift from exhaustion to stroke can happen in minutes

  Heat exhaustion and heat stroke sit on the same spectrum but require completely different responses. Heat exhaustion means the body is struggling but still working — it produces warning signs like heavy sweating, pale and clammy skin, weakness, dizziness, nausea or vomiting, and headache. The right response: move immediately to a cool place, remove excess clothing, sip cool water, and cool the skin with damp cloths. Get medical help right away if vomiting starts, symptoms worsen, or they don’t improve within 30 minutes. Heat stroke is a medical emergency. The body’s cooling system has failed. The most dangerous sign is that sweating stops — the skin becomes hot and dry even in extreme heat. Body temperature can spike to 106°F or higher within 10 to 15 minutes. Confusion, disorientation, slurred speech, seizures, and loss of consciousness may follow. Call 911 immediately. Do not give fluids to someone who is unconscious or confused. Move the person to shade or air conditioning and cool them with whatever is available while waiting for help.
• 6
  Who is most at risk during a heat advisory or heat wave? Adults 65+ are the highest-risk group · People without home air conditioning · Outdoor workers · Children under 5 · People with heart disease, diabetes, kidney disease, respiratory conditions · People taking diuretics, antihistamines, or certain blood pressure medications

  Research published in a 2026 medical journal confirmed that heat-wave-related mortality in adults over 65 increased approximately 85% between 2000 and 2021 — a staggering rise that reflects both the intensification of heat events and the aging of the population. An older adult’s body is less efficient at regulating temperature: sweat production declines, thirst sensation diminishes (so dehydration happens without feeling thirsty), and the cardiovascular system has to work harder to push blood toward the skin for cooling. Certain medications compound the problem significantly: diuretics (water pills) reduce the body’s fluid reserves; antihistamines and antidepressants impair sweating; beta-blockers and calcium channel blockers reduce the heart rate response that helps cool the body. If you or a loved one takes any of these medications, talk to a doctor before the heat season about whether your dosing or hydration plan needs adjustment during heat events. One widely cited Harvard Medicine article estimates that roughly 80% of the 12,000 Americans who die from heat each year are over 60.
• 7
  Where can I find a free cooling center near me? Call 2-1-1 (free, nationwide) · Visit heat.gov/cooling-centers · Text your zip code to your state emergency management agency · Cooling centers open in libraries, senior centers, community centers, and places of worship

  Every state has cooling centers that open during heat emergencies — many of them free, air-conditioned public spaces in libraries, senior centers, community centers, schools, and sometimes houses of worship. The fastest way to find one is to call 2-1-1 (the United Way’s national hotline, free from any phone) and say you need a cooling center — they will tell you the nearest open location and whether transportation assistance is available. In New York, calling 311 connects you to cooling center information. In major cities like Phoenix, Houston, and Chicago — which have faced particularly dangerous heat seasons — the city’s public health department website maintains updated cooling center directories. Some cooling centers only activate during declared heat emergencies, so always call ahead or check online rather than showing up and finding the doors closed. LIHEAP (the Low Income Home Energy Assistance Program) also provides funding to help qualifying low-income households pay cooling costs — contact your state’s energy office or benefits.gov to check eligibility.
• 8
  Does a fan help during a heat wave or is air conditioning necessary? Fans help below 95°F · Above 95°F, fans can accelerate heat stroke risk by blowing hot air across the skin · The CDC recommends not relying on fans alone during heat waves · Air conditioning is the most effective protection

  This is one of the most consequential misunderstandings about heat safety. Fans cool you by evaporating sweat — a process that works efficiently when air temperature is below roughly 95°F. But when the air itself is hotter than your skin, a fan blowing across your body moves hot air past you rather than cooling you, potentially accelerating your body’s heat absorption. The CDC explicitly advises not relying on fans alone during periods of extreme heat. If you do not have air conditioning at home, the priority is getting to an air-conditioned environment for at least a few hours during the hottest part of the day — typically from noon to 6 p.m. Public cooling centers, air-conditioned grocery stores, malls, libraries, and movie theaters all serve this purpose. Low-income seniors and households without air conditioning may be eligible for free AC units through LIHEAP or state-level cooling assistance programs. Contact your local Area Agency on Aging (findable at eldercare.acl.gov) for local program referrals.

Knowing the difference before an emergency happens could save a life. Print this section and put it on your refrigerator if you care for anyone elderly, very young, or chronically ill.

Use the buttons below to find cooling centers, urgent care clinics, pharmacies, or senior centers near you. Always verify cooling center hours by calling ahead — some only open during declared heat emergencies.