Call 911 immediately if someone in the heat becomes confused, collapses, or has a seizure. That is heat stroke. Do not wait for dry skin — a person in heat stroke may still be sweating. It is life-threatening and can cause permanent organ damage within minutes. Start cooling them while you wait for paramedics.
Every Arizona summer, our emergency rooms see the same preventable pattern: someone worked, walked, or golfed a little too long, felt unwell, decided to push through, and arrived hours later much sicker than they needed to be.
Heat illness is a spectrum, and the difference between the manageable end and the dangerous end is a handful of specific signs. Learning them takes two minutes and they are genuinely worth knowing before you need them.
Heat cramps — the first warning
Painful muscle cramps, usually in the legs, arms, or abdomen, often with heavy sweating.
What to do: stop the activity, get into shade or air conditioning, sip water or an electrolyte drink, and gently stretch. Do not go back out for the rest of the day.
Heat cramps are your body’s early notice. People who respond to them here rarely end up in our waiting room.
Heat exhaustion — the serious middle
The body is losing the fight but still compensating. Look for:
- Heavy sweating, with cool and clammy skin
- Weakness, fatigue, dizziness
- Headache
- Nausea or vomiting
- A fast, weak pulse
- Muscle cramps
- Pale skin
What to do: move to a cool place immediately. Lie down and elevate the legs. Loosen clothing. Sip cool fluids. Apply cool wet cloths, or take a cool shower.
Seek medical care if: the person vomits, or symptoms worsen or last longer than an hour — that is the National Weather Service’s threshold, not ours. Go sooner if the person has heart disease, kidney disease, or takes diuretics or blood pressure medication.
Escalate to 911 the moment confusion appears. Heat exhaustion becomes heat stroke quickly, and the transition is not always gradual.
Heat stroke — a true emergency
Core temperature has risen past the point where the body can regulate itself. This is an emergency in the same category as a stroke or a heart attack.
Signs:
- Confusion, agitation, slurred speech, or loss of consciousness — the single most important sign
- Body temperature above 103°F (39.4°C)
- Hot skin that may be dry, or still damp — the National Weather Service lists heat stroke skin as “hot, red, dry or damp”, so the old “always dry skin” rule will mislead you, especially in heat stroke brought on by exertion
- Rapid, strong pulse
- Throbbing headache, nausea, vomiting
- Seizure
What to do, in this order:
- Call 911. Do not drive them yourself if you can avoid it — cooling needs to begin now, and paramedics can start treatment en route.
- Start cooling immediately. Shade or indoors. Remove excess clothing. Cool water over the body, a cool bath if available, ice packs to the neck, armpits, and groin. Fan them.
- Do not give fluids. The National Weather Service’s heat stroke first aid says exactly that, and the reason is that someone confused or not fully alert may choke.
- Keep cooling until help arrives. Minutes matter more than anything else you can do.
Heat stroke can damage the brain, kidneys, heart, and muscles. Rapid cooling is the treatment, which is why starting before the ambulance arrives genuinely changes outcomes.
Who is at higher risk
- Adults over 65, and infants and young children
- Anyone with heart, lung, or kidney disease, diabetes, or obesity
- People taking diuretics, beta blockers, antihistamines, antipsychotics, or stimulants
- Outdoor workers, athletes, and anyone new to the desert who has not acclimatized
- Anyone who has had heat illness before
Two Arizona-specific realities worth naming. Monsoon humidity makes everything worse — sweat evaporates less efficiently, so the body’s main cooling mechanism becomes less effective at the same temperature. And a parked car is not a shaded place to wait. In a National Weather Service demonstration the interior went from a safe temperature to an unsafe one in just over two minutes; a dark dashboard or seat reaches 180°F and beyond; and cracking the windows “does not significantly decrease the heating rate”. Children and pets must never be left inside one, even briefly.
Preventing it
- Drink before you are thirsty; thirst lags behind dehydration
- Shift outdoor activity to early morning, and skip the hours from about 10 AM to 6 PM in high summer
- Light, loose, light-colored clothing; a wide-brimmed hat
- Take real breaks in air conditioning, not just shade
- Give yourself one to two weeks to acclimatize if you are new to the heat or returning after time away
- Check on elderly neighbors during heat warnings — this is the single highest-value thing on this list
- Never leave anyone in a parked car
For official forecasts and heat warnings, the National Weather Service publishes Arizona-specific guidance at weather.gov/safety/heat-illness, and the CDC’s heat health resources are at cdc.gov/heat-health.
We are open all summer, all night
Heat illness does not keep business hours, and the dangerous hours in Arizona often run well past sunset — the body keeps struggling long after the temperature peaks.
- Fountain Hills Emergency Room — 9700 N Saguaro Blvd, Fountain Hills, AZ 85268 · (602) 671-7990 · open 24/7
- El Mirage Emergency Room — 12000 N El Mirage Rd, El Mirage, AZ 85335 · (480) 237-4922 · open 24/7
Both have labs on site, which matters here: heat illness is assessed partly through blood work on kidney function, electrolytes, and muscle breakdown. Getting those results during your visit rather than days later is the difference between treating the problem and guessing at it.
Find your nearest 24/7 IHCS emergency room →
Sources
Every link below was opened and read on 13 September 2026. The symptom lists, the 103°F threshold, the one-hour rule and the instruction not to give fluids are the National Weather Service’s, not ours.
- Heat cramps, heat exhaustion and heat stroke: the signs and the first aid. Heat Cramps, Exhaustion, Stroke, National Weather Service.
- How fast a parked car turns dangerous. Children, Pets and Vehicles, National Weather Service.
- Heat risk factors and the medications that raise them. Clinical Overview of Heat, Centers for Disease Control and Prevention — written for clinicians rather than patients.
Three things on this page are ours and are not in those sources: the note about monsoon humidity, the one-to-two-week acclimatization window, and the prevention list. They are general guidance, not thresholds to act on by themselves. Hours, addresses and phone numbers come from IHCS’s own records.
This article is general health information, not medical advice, and it cannot account for your specific situation. If you suspect heat stroke, call 911 immediately.