Low Desert Almanac

Heat-Illness Triage Guide

A step-by-step guide to recognising and responding to heat illness, following CDC and Maricopa County Public Health guidance. Call 911 first for confusion, fainting or hot dry skin.

Heat & Safety

What do these symptoms mean, and what do I do now?

Before anything else

If someone is confused, has slurred speech, has fainted, is having a seizure, or feels very hot, call 911 now and start cooling them. Do not use this page first.

Tick what you are seeing

Emergency signs

Everything else

Who the CDC says is at higher risk

Adults aged 65 and over
More prone to heat-related health problems.
Infants and young children
They rely on others to keep them cool and hydrated.
People with chronic conditions
Hot days are especially dangerous with a chronic medical condition.
People without air conditioning
Named by the CDC as a risk group in its own right.
Athletes
More likely to become dehydrated and get heat-related illness.
Outdoor workers
More likely to become dehydrated and get heat-related illness.
Pregnant people
Pregnancy can make you more likely to get sick when it is very hot.

If you ticked an emergency sign

Heat stroke

A medical emergency. The body can no longer control its temperature, sweating can fail, and the body temperature can reach 106 °F or higher within ten to fifteen minutes.

What to do CDC National Institute for Occupational Safety and Health: "Heat-related Illnesses"

  1. Call 911 for emergency medical care.
  2. Stay with the person until emergency medical services arrive.
  3. Move them to a shaded, cool area and remove outer clothing.
  4. Cool them quickly: a cold water or ice bath if possible, wet the skin, place cold wet cloths on the skin, soak clothing with cool water.
  5. Circulate the air around them to speed cooling.
  6. Place cold wet cloths or ice on the head, neck, armpits and groin, or soak the clothing with cool water.

https://www.cdc.gov/niosh/heat-stress/about/illnesses.html

The part people get wrong

Do not wait for the skin to be dry. The CDC lists "hot, dry skin or profuse sweating" as one symptom: a person in heat stroke can still be sweating heavily, and waiting for dryness is how the emergency gets missed.

Also matches what you ticked

The five conditions, by how fast they move

Ordering, not timing. The positions show which conditions the CDC treats as emergencies and which it treats as things you handle yourself: a triage order, not a clock.

Heat illnesses ordered by urgency Heat stroke and rhabdomyolysis need emergency care. Heat exhaustion and heat syncope need medical evaluation. Heat cramps, heat rash and sunburn are handled at home unless they get worse. Emergency: call 911 Heat stroke · Rhabdomyolysis Medical care Heat exhaustion · Heat syncope At home, unless it worsens Heat cramps · Heat rash · Sunburn

Grouping from the CDC/NIOSH heat-illness page and its rhabdomyolysis page. Heat stroke’s own timeline is the only hard number on the chart: the CDC says the body temperature can reach 106 °F or higher within ten to fifteen minutes.

What this page is

A checklist that routes you to published guidance and quotes it without paraphrasing. It is not a diagnosis, it cannot tell heat exhaustion from the start of heat stroke in someone it cannot see, and it does not replace a call to 911. Every symptom line and every step below comes from the source named above it.

How this works

Method

Why this tool quotes rather than paraphrases

Almost every page on this site is written in the site's own words, working from a source. This one is not, and the reason is the subject matter. A paraphrased first-aid step is a step somebody might follow, and the cost of a paraphrase that loses a qualifier is higher here than anywhere else the site goes.

So the symptom lists and the numbered steps on the panel are the CDC's own wording, in the CDC's own order, from the NIOSH heat-illness page. The one place this site adds a sentence of its own is the "part people get wrong" box under each condition, which is labelled as this site's and exists because the CDC's wording contains an easily-missed detail.

The detail the CDC buries, and why it matters

The CDC's symptom list for heat stroke includes, in a single line: hot, dry skin or profuse sweating.

Almost everybody who has heard of heat stroke has heard the first half. The second half is the one that gets people killed, because the popular image, a person who has stopped sweating, is only one of the two presentations the CDC describes. A person in heat stroke can be sweating heavily. Waiting for the skin to go dry before calling 911 is waiting for a sign that may never come.

That is the single most important sentence on this page, and it is the reason the tool exists at all. The rest of the guidance is available from the CDC in two clicks. The tool's contribution is putting the right paragraph in front of somebody in the ten seconds they have to decide.

What the CDC changed, and why the old page is gone

Until recently the detailed CDC symptom and first-aid lists lived on a page called "Warning Signs and Symptoms of Heat-Related Illness", at a URL that many sites still link to. That page no longer carries those lists. The URL now serves the CDC's general heat-and-health page, which has one short and much less useful symptom paragraph and no first-aid steps at all.

The detailed guidance moved to the NIOSH page cited above, which is the page this tool uses. It is worth knowing that this happened, because a large amount of heat-safety material online, including material from official-looking sources, still quotes the older page as if it were current. When this site checked in October 2026, the NIOSH page was live and carried the full lists.

Why the tool is biased towards the emergency answer

The tool returns the heat-stroke guidance if any emergency sign is ticked, regardless of what else is ticked alongside it. That is a deliberate asymmetry and it is not neutral. The two possible errors cost very different amounts: over-reacting costs an ambulance ride and some embarrassment, and under-reacting can cost a life. A tool that tried to be even-handed between those two would be making the wrong trade on purpose.

The same reasoning shapes the ordering of everything else. Rhabdomyolysis sits in the emergency group even though it is not usually thought of as an emergency, because the CDC says its consequences include kidney failure and death and that its symptoms cannot identify it. Heat exhaustion sits above heat cramps, and the CDC's first step for it is a clinic or an emergency room rather than a rest at home.

The four conditions the tool covers, and one it does not

The CDC's heat-illness list is heat stroke, heat exhaustion, rhabdomyolysis, heat syncope, heat cramps and heat rash. All six are here, plus sunburn, which is not on the CDC's heat-illness list, lives on its skin-cancer pages instead, and is the most common thing a day in the Phoenix sun actually produces.

What the tool does not do is separate any of this by age or condition. The CDC publishes one set of symptom lists and a separate list of who is at higher risk, and this page keeps that structure rather than inventing a paediatric version the CDC has not written. The risk list is in the panel on the left, in the CDC's own words.

How to use it in the moment

In an actual emergency, do not use this page. Call 911, move the person out of the sun, and start cooling them (water, cold cloths, air movement) while you wait. The page exists for the other case: somebody is not right after working outside, you are not sure how bad it is, and you want to know which paragraph of official guidance applies before you decide what to do next.

If that decision takes more than a minute, the answer is 911. The tool is fast, but it is not faster than the phone.

Sources

Where this came from

Every figure this tool uses was read from the source named above on 10 October 2026. Anything still waiting on a check is listed in the site's data notes rather than shown here as if it were settled.

Limits and assumptions

Read this

Before you rely on this

This tool works from climate normals and published guidance, not from live weather. It describes a typical day for the month or date you chose, which is useful for planning and useless as a forecast.

  • This is not a diagnosis and it cannot make one. It is a checklist that routes you to the right paragraph of published guidance. Several of these conditions share symptoms, and no checklist can tell heat exhaustion from the early stage of heat stroke in a person it cannot see.
  • When in doubt, call 911. That instruction is not a hedge. It is the guidance. Heat stroke is fatal if treatment is delayed, and the CDC’s first aid for heat exhaustion is a clinic or an emergency room, not a rest at home.
  • The tool is deliberately biased towards the emergency answer. Ticking anything in the first group of symptoms returns the heat-stroke guidance regardless of what else is ticked, because the cost of over-reacting here is an unnecessary ambulance ride and the cost of under-reacting is a death.
  • Dark urine, severe muscle aches and being unable to finish a workout you could do before all point at rhabdomyolysis, which the CDC says cannot be identified from symptoms alone and needs a blood test. The tool flags it; it cannot rule it out.
  • The symptom wording is the CDC’s and NWS Phoenix’s, aimed at workers in a workplace setting in some cases. The word "worker" appears in the CDC’s steps because that is how the CDC wrote them. On this page it means the person in front of you.
  • Nothing here covers children, pregnancy, older adults or people on medication as separate cases, because the CDC does not publish separate symptom lists for them: it publishes a risk list, which is on the page. If the person is in one of those groups, treat the same symptoms as more serious, not less.
  • No dosages, no medication advice, and no guidance on whether to stop a prescribed medicine in the heat. Those are questions for a clinician or a pharmacist.

Questions

Short answers
What are the warning signs of heat stroke?
The CDC lists confusion or altered mental status, slurred speech, loss of consciousness, hot dry skin or profuse sweating, seizures, and a very high body temperature. Read that list again and notice the fourth item: the CDC says "hot, dry skin OR profuse sweating". The dry-skin version is the one everybody knows and it is not the only version. Someone in heat stroke can be sweating heavily.
How long do you have?
The CDC puts a number on it: in heat stroke the body temperature can rise to 106 °F or higher within ten to fifteen minutes. That is the clock the first aid is racing. It is also why the instruction is to cool the person first and move them second: cooling starts on the spot, not in the car on the way to the hospital.
Is heat exhaustion an emergency?
The CDC treats it as one: its first step is to take the person to a clinic or emergency room for medical evaluation and treatment, and to call 911 if medical care is unavailable. Most people who have had heat exhaustion stayed home and felt better, and that is not evidence the guidance is wrong. It is evidence that heat exhaustion usually resolves. The guidance exists for the times it does not.
What is rhabdomyolysis and why is it on this page?
Rhabdo is what happens when damaged muscle releases its proteins into the blood, where they can cause dangerous heart rhythms, seizures and kidney failure. It is on this page because the CDC names heat exposure and physical exertion as its two main risk factors, which describes an afternoon of yard work in July. The signs are muscle aches or cramps more severe than you would expect, and dark urine the colour of tea or cola. The CDC is explicit that you cannot tell from symptoms alone whether you have it and that only a blood test settles it.
Should I use salt tablets?
No. The CDC says to avoid them, in those words, in its heat-cramps first aid. Its recommendation is water plus a snack or a sports drink that replaces carbohydrates and electrolytes, taken every fifteen to twenty minutes. It also names three reasons to get medical help for cramps: heart problems, a low-sodium diet, or cramps that have not subsided within an hour.
Does drinking water prevent all of this?
It prevents the fluid and salt part of it, and it does nothing at all for the part that matters most. Heat stroke is a failure of the body’s temperature control, and a well-hydrated person can still have one. The CDC’s risk list includes athletes and outdoor workers, who are not usually the dehydrated ones. Hydration is one layer; shade, timing, and knowing when to stop are the others, and the [Heat-Safe Hours Planner](/tools/heat-safe-hours-planner/) is the tool on this site for the timing part.