Korea's heat alerts: the three tiers
Advisory is 33C felt, warning 35C for two days, critical 38C for one day
The three lines
- Korea rebuilt its heat alert system into three tiers on 1 June, the first change in 18 years
- Advisory and warning need two consecutive days; the critical tier fires on a single day
- For suspected heat stroke call 119, cool with ice packs, and give no fluids if unconscious
Key questions
- What are the criteria for Korea's heat alerts
- An advisory is issued when the felt temperature is expected to reach 33C for two or more consecutive days, a warning at 35C on the same two-day basis, and a critical alert at 38C expected for a single day.
- What is the new critical heat alert
- A third tier added on 1 June 2026, above the existing advisory and warning. It is the first restructuring of the system in 18 years and the first tier that triggers on a one-day forecast rather than two.
- What should you do for suspected heat stroke
- Call 119 immediately, move the person into shade, and cool them with ice packs at the neck, armpits and groin. Do not give fluids to anyone who is unconscious or cannot swallow reliably.
Korea rebuilt its heat alert system on 1 June 2026, the first structural change in eighteen years. Two months later the new top tier was in force across the southeast while a station in Yangsan recorded 41.4C. This is a reference piece on what the tiers mean and what the clinical response actually is, because both are routinely reported in fragments.
1. The three tiers
The system runs on felt temperature — the heat index combining air temperature and humidity — rather than air temperature alone. That matters in a Korean summer, where humidity frequently makes 33C feel considerably worse than the same reading in a dry climate.
| Tier | Threshold (felt) | Duration required |
|---|---|---|
| Advisory | 33C | two or more consecutive days expected |
| Warning | 35C | two or more consecutive days expected |
| Critical | 38C | a single day expected |
The duration column is the part most often dropped in reporting, and it is the design decision that matters. Advisory and warning both require a sustained pattern, on the reasoning that consecutive hot days compound physiological load. The critical tier abandons that requirement: a single forecast day at 38C is enough, because at that level the risk is acute rather than cumulative.
2. What to do
For heat exhaustion — heavy sweating, weakness, nausea, headache, but consciousness intact — move to shade or air conditioning, loosen clothing, and give cool water or an electrolyte drink in small amounts.
For suspected heat stroke, the response is different and time-critical. The distinguishing signs are a body temperature above 40C, skin that is hot and often dry rather than sweating, and altered consciousness — confusion, slurred speech, collapse.
- Call 119 immediately. Do not wait to see whether the person improves.
- Move them into shade and remove excess clothing.
- Cool aggressively with ice packs at the neck, armpits and groin, where large vessels run close to the surface.
- Do not give fluids to anyone unconscious or unable to swallow reliably. Aspiration is a real risk.
The distinction matters because heat stroke has a mortality curve measured in tens of minutes. Cooling before the ambulance arrives is not optional first aid; it is the intervention.
3. Where the season stands
Cumulative heat-illness cases reached 1,638 with 12 deaths as of 31 July. Officials described the death toll as running at roughly 75% of the equivalent point last year, against higher peak temperatures — which suggests the alert changes and the cooling-centre network absorbed part of the load, though that is an inference rather than a measured effect.
These totals are provisional. Korean heat-illness deaths are reclassified after cause-of-death review, so the final figure will not be settled until autumn. The temperature record that triggered the first critical alerts is covered in a companion piece published the same day.