The National Weather Service put an unusual instruction in its heat products for Missouri this week. Alongside the standard advice about fluids and air conditioning, forecasters told residents to "know the signs and symptoms of heat exhaustion and heat stroke."
That is worth taking literally, because the two conditions can start the same way and only one of them is survivable without emergency care. Heat exhaustion usually responds to cooling and rest. Heat stroke kills people who are given a glass of water and told to sit down.
Extreme Heat Warnings covering much of Missouri and adjacent parts of Kansas and Illinois ran through Tuesday morning, with forecast heat index values reaching 110 in central and east central Missouri, 113 in west central Missouri and eastern Kansas, and 115 in the Springfield forecast area. Heat Advisories remain in effect into Tuesday evening, with heat index values up to 110 in parts of southwest and south central Missouri.
Advisory-level heat is not safe heat. It is the level at which people who have already spent two or three days in a hot house start showing up in emergency departments.
The Line Between Exhaustion and Stroke
The distinguishing sign is not temperature, and it is not how bad the person says they feel. It is whether they are thinking and behaving normally.
Heat exhaustion typically presents with heavy sweating, skin that is cold, pale and clammy, a fast weak pulse, nausea or vomiting, muscle cramps, dizziness, headache, tiredness, and sometimes fainting, according to CDC guidance on heat-related illness. The person is miserable but oriented.
Heat stroke looks different in a specific way. Body temperature reaches 103 degrees or higher. Skin may be hot and red and either dry or damp. The pulse is fast and strong rather than weak. And critically, the person becomes confused, agitated, slurred in their speech, unable to keep their balance, or loses consciousness.
The CDC's occupational guidance notes that in heat stroke the body's cooling system fails outright and core temperature can climb to 106 degrees or higher within 10 to 15 minutes, with permanent disability or death possible without emergency treatment.
Two practical rules follow. Confusion or altered behavior in someone who has been in the heat means call 911, not wait and see. And do not give fluids by mouth to a person who is confused or unconscious, because they can aspirate.
While waiting for paramedics, move the person somewhere cooler, remove excess clothing, and cool them aggressively with cold wet towels or ice packs at the neck, armpits and groin, or with a cool bath or shower if that is available. Fanning wet skin speeds cooling. Stay with them and watch their breathing.
For heat exhaustion, move to a cool place, loosen clothing, apply cool cloths, and sip water or an electrolyte drink. Call 911 if symptoms worsen, last longer than an hour, or if chest pain or shortness of breath develops.
What the Warnings Actually Ask People to Do
The safety language in the Missouri products is specific and unglamorous. Forecasters advised residents to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances.
That last instruction is not boilerplate. A vehicle interior can climb dozens of degrees above the outside air within minutes, and cracking a window does not meaningfully slow it.
The check-on-neighbors line is the one with the most public health weight. Heat deaths in American cities cluster among older adults living alone, often in homes with air conditioning that is broken, unaffordable to run, or simply not turned on. A phone call is a weak substitute for someone physically confirming that the house is cool and the person is alert.
Fans deserve a specific caution. Ready.gov advises against relying on a fan as a primary cooling device, noting that fans create airflow and a false sense of comfort without reducing body temperature in genuinely dangerous heat. Anyone without working air conditioning should plan to spend the hottest hours in a library, shopping center, community center or cooling center rather than in front of a fan.
Outdoor Workers Are the Group the Advisories Single Out
The Missouri products carried an explicit occupational instruction. To reduce risk during outdoor work, forecasters relayed, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air-conditioned environments. The products also advised rescheduling strenuous activity to early morning or evening and wearing lightweight, loose-fitting clothing.
Construction crews, roofers, landscapers, roadway workers, agricultural laborers, warehouse and delivery staff, and utility crews carry most of this risk. So do people whose jobs are indoors but unconditioned, including kitchen workers and anyone in an uncooled warehouse.
Acclimatization matters more than most people realize. Workers who are new to a job, returning from time off, or reassigned to outdoor duty are disproportionately represented in serious occupational heat illness, because the body takes days to adapt to working in heat. A crew's newest member is often its most vulnerable.
Who Faces the Highest Risk
Risk is not distributed evenly. Adults over 65 lose some of their ability to sense thirst and to shed heat efficiently. Infants and young children cannot regulate temperature well and cannot remove themselves from a hot room or car. People with heart disease, chronic lung disease, kidney disease, diabetes, obesity or a mental illness that affects judgment face elevated risk, as do people experiencing homelessness and those without reliable air conditioning.
Medications are an underappreciated factor. Some diuretics, blood pressure medicines, antihistamines, antipsychotics, antidepressants and stimulants can impair sweating, alter fluid balance or blunt thirst. That is not a reason to skip a dose. It is a reason to ask a pharmacist or prescriber one question before the next hot stretch: do any of my medications make me more vulnerable to heat, and what should my plan be on very hot days?
Athletes and anyone exercising outdoors should also know that exertional heat stroke can develop in a fit young person in under an hour, and it often presents with sweaty rather than dry skin, which is why the mental status change is the sign to watch.
What to Do Over the Next Few Days
Check current alerts for your specific county rather than relying on a regional headline, because these products are issued and revised several times a day. Local National Weather Service pages and heat.gov both carry current conditions.
Drink water on a schedule rather than waiting for thirst, and limit alcohol and heavy caffeine. Plan errands, yard work and exercise for early morning. Identify now where you would go if your air conditioning failed on a 100-degree afternoon. And pick two people to check on in person, ideally an older relative or neighbor living alone.
Heat is the deadliest weather hazard in the United States in most years, and it kills quietly, in bedrooms and parked cars and back yards rather than dramatically. The single most useful thing a reader can carry out of this article is the bright line: someone who feels awful in the heat probably has heat exhaustion, and someone who is not thinking or acting normally has heat stroke until proven otherwise. That second one is a 911 call.
Frequently Asked Questions
What is the difference between heat exhaustion and heat stroke? Heat exhaustion involves heavy sweating, clammy skin, a weak pulse, nausea, and dizziness in someone who is still thinking clearly. Heat stroke involves a body temperature of 103 degrees or higher, hot skin, a strong pulse, and confusion or loss of consciousness.
When should I call 911? Immediately if someone in the heat becomes confused, agitated, slurs their speech, cannot keep their balance, or passes out. Also call if heat exhaustion symptoms worsen, last more than an hour, or involve chest pain or shortness of breath.
Should I give the person water? Not if they are confused or unconscious. Cool them instead and wait for paramedics. Someone with heat exhaustion who is fully alert can sip water or an electrolyte drink.
Is a fan enough if I have no air conditioning? No. Ready.gov advises against relying on a fan as a primary cooling device in dangerous heat. Spend the hottest hours in an air-conditioned public building.
What does the OSHA recommendation say? The weather service products relayed OSHA's recommendation to schedule frequent rest breaks in shaded or air-conditioned environments for outdoor work.
Who is most at risk? Adults over 65, infants and young children, people with chronic heart, lung, kidney or metabolic disease, outdoor workers, people without air conditioning, and people taking certain medications.
How long do these alerts last? Heat products are revised several times daily. Check your county's current National Weather Service alert rather than relying on a headline from a previous day.
