South Korea heat alerts in 2026: 33°C, 35°C and 38°C
Korea’s new severe heat warning starts at a 38°C apparent temperature or 39°C air temperature. See how alerts work and what residents and travelers should do.
Contents
- What do Korea’s 33°C, 35°C and 38°C alerts mean?
- How hot is South Korea on July 27?
- What do Korea’s 1,070 heat-illness cases show?
- What changes for outdoor workers?
- What should residents and travelers do first?
- Can the warning and case count be taken at face value?
- Why did Korea add a higher alert in 2026?
South Korea’s severe heat warning is a new top-tier alert for 2026. It can be issued in an area already experiencing warning-level heat when the daily maximum apparent temperature is forecast to hit 38°C (100.4°F), or the actual air temperature is expected to reach 39°C (102.2°F). The Korea Meteorological Administration, or KMA, used it for the first time in Pohang and Gyeongsan on July 12. The official instruction at this level is blunt: stop, move to a cool place, and check on other people (KMA and Ministry of the Interior and Safety announcement).
- 38°C
- Severe-warning apparent temperatureOr an actual high of 39°C
- 31–37°C
- July 27 national high forecastKMA update at 5 a.m.
- 1,070
- Provisional 2026 heat-illness casesMay 15 through July 21
- 4
- Suspected heat-related deathsSame surveillance period
What do Korea’s 33°C, 35°C and 38°C alerts mean?
The three thresholds describe different combinations of intensity and duration. A heat advisory applies when the daily maximum apparent temperature is expected to reach at least 33°C for two or more days. A heat warning uses 35°C for the same duration. The severe warning sits above that: an area has already met warning conditions, then faces an apparent temperature of 38°C or an air temperature of 39°C.
| Korean alert | Forecast threshold | Practical reading | Immediate response |
|---|---|---|---|
| Heat advisory | Maximum apparent temperature of 33°C or more for at least two days | Prolonged outdoor activity becomes risky | Secure water, shade and rest; shorten midday plans |
| Heat warning | Maximum apparent temperature of 35°C or more for at least two days | Healthy adults can become ill during sustained work or exercise | Reschedule outdoor activity and increase checks on vulnerable people |
| Severe heat warning | In a warning-level area, apparent temperature 38°C or air temperature 39°C | Extreme heat can cause serious harm after much shorter exposure | Stop outdoor activity, enter cooling and check family, neighbors and workers |
Korea uses apparent temperature because humidity and wind change how quickly the body can shed heat. KMA says a 10-percentage-point rise in humidity adds roughly 1°C to apparent temperature under its calculation. The separate 39°C air-temperature trigger catches a different problem: the air itself can be extreme even when lower humidity keeps the apparent-temperature formula below 38°C.
The first alert shows how the rule works. Pohang and Gyeongsan had already recorded maximum apparent temperatures of at least 35°C on July 10 and 11. KMA then expected apparent temperature of at least 38°C, or an actual high of 39°C, on July 12. This is accumulated stress followed by an extreme peak. It is more serious than a single hot afternoon.
How hot is South Korea on July 27?
KMA’s national forecast issued at 5 a.m. on July 27 put the day’s highs at 31–37°C. The observed national range on July 26 was 29.2–37.3°C. Forecast highs were 31–36°C for July 28, 31–37°C for July 29 and 30–38°C for July 30. These are ranges across the country, not a single Seoul reading (KMA national forecast).
That distinction matters to travelers. A shower in central Seoul does not cancel a warning in inland Gyeongsang. A short rain can cool the air, then leave more humidity behind. Check the warning for your destination and route, not the weather icon saved for your hotel.
KMA attributed the first severe episode to hot air stacked through several layers of the atmosphere under the Tibetan high aloft and the North Pacific high below it. Heat built during the day and had less room to escape overnight. Korea also introduced a tropical-night advisory in 2026 because high overnight temperatures cut the body’s recovery time. A day that begins after poor sleep and a hot apartment is not physiologically the same as an isolated 35°C day.
What do Korea’s 1,070 heat-illness cases show?
The Korea Disease Control and Prevention Agency, or KDCA, counted 1,070 heat-illness patients and four suspected deaths from May 15 through July 21. Twenty-five patients were reported on July 21 alone. The figures come from 516 participating emergency departments, and KDCA labels them provisional sample surveillance, not a complete count (KDCA daily surveillance report).
The cumulative number was lower than the 1,732 patients and nine suspected deaths recorded by the same point in 2025. That comparison is useful, but it is not a season forecast. Heat damage arrives in bursts. KDCA says about 30% of all 2025 patients—1,341 people—fell ill from July 20 through July 31, a 12-day stretch.
Source: Korea Disease Control and Prevention Agency, May 14, 2026
| 2023 | 2818 |
|---|---|
| 2024 | 3704 |
| 2025 | 4460 |
The annual totals rose from 2,818 in 2023 to 3,704 in 2024 and 4,460 in 2025. The 2025 total was the second-highest since surveillance began in 2011, just 66 cases below the 2018 record of 4,526. Nearly four in five 2025 cases occurred outdoors. Outdoor workplaces accounted for 1,431 patients, fields for 542 and roadsides for 522 (KDCA 2026 surveillance launch).
The chain does not stop at a medical diagnosis. Long heat exposure raises fatigue; hot nights reduce recovery; lower concentration can contribute to falls, traffic crashes and mistakes around machinery. Delayed construction, crop losses and electricity peaks sit in other datasets. The health count is one visible slice of a broader disruption.
What changes for outdoor workers?
Korean workplace guidance uses the apparent temperature at the worksite, which can differ from the nearest weather station. At 33°C or above, workers should receive at least a 20-minute break within every two hours. At 35°C, the guidance moves to 15 minutes every hour and stopping outdoor work during the hottest hours unless it is unavoidable. At 38°C, outdoor work should stop except for emergency operations needed for disaster and safety management (KMA, labor ministry and KOSHA worker guidance).
| Worksite apparent temperature | Minimum response |
|---|---|
| 31°C or above | Water, cooling or airflow, a nearby rest area and heat-safety checks |
| 33°C or above | At least 20 minutes of rest within every two hours; extra rest for high-risk or high-intensity work |
| 35°C or above | Fifteen minutes of rest each hour; stop outdoor work during peak heat when possible |
| 38°C or above | Stop outdoor work except emergency safety operations; restrict exposure for heat-susceptible workers |
An official alert can lag the microclimate around asphalt, glass walls, boilers, welding equipment or an unventilated warehouse. Employers still need on-site measurements. A nominal break also fails if workers spend most of it walking to a tent that is nearly as hot as the work area. Cooling time, water access and permission to halt the job matter more than a box ticked on a schedule.
This is where the severe alert has teeth. It gives a site manager a public threshold for stopping production. Without that authority, the pressure to finish a shift or delivery can beat a general request to “be careful.”
What should residents and travelers do first?
Cancel or delay hiking, running, open-air festivals and long walking tours in a severe-warning area. Moving the same plan two hours later may not solve the problem if a tropical night keeps temperatures high. Go into air conditioning, drink water before thirst develops when medically appropriate, and avoid leaving anyone in a parked car.
Check older adults, young children and people with cardiovascular disease, diabetes or other conditions that affect heat tolerance. Ask concrete questions: Is the air conditioner running? Have they had water? Are they dizzy, nauseated, confused or cramping? A generic “Are you okay?” often gets an automatic yes.
Call 119 if someone becomes confused, loses consciousness, has a seizure or has very hot skin. Move the person into shade or air conditioning, loosen clothing and begin cooling while help is on the way. Do not force water into someone who cannot swallow normally.
Visitors should also know that Korea expanded its warning map from 183 to 235 zones in 2026. Mountain, coastal and city districts within one province may carry different alerts. KMA publishes an English warning page, while its worker materials are available in multiple languages. Phone emergency alerts may arrive in Korean, so checking the map directly is a safer backup.
Readers who prefer the source terms in Korean can use the Korean-language companion to this warning guide. KMA’s live map still takes priority because alert areas can change during the day.
Can the warning and case count be taken at face value?
Use the warning as a decision threshold, not a personalized prediction. An official station cannot measure every sunlit schoolyard, rooftop room, greenhouse or delivery truck. Medication, protective clothing, alcohol, poor sleep and a person’s health can move the danger line lower.
The case count has a different limitation. It includes patients who reached participating emergency departments and were reported through the network. A person treated at a clinic or at home may not appear. A suspected heat death may later receive a different cause in national mortality statistics. It would be wrong to say there were “only” 1,070 cases, but it would also be speculation to multiply that number by an invented factor.
There is a policy gap too. Better alerts do not create air conditioning, paid rest or an open cooling center. A worker paid only for completed hours may struggle to follow a stop-work instruction. A resident worried about the electricity bill may keep the air conditioner off. The system should eventually be judged by what happens after an alert: work stoppages, cooling-center access, heat-related injury and deaths.
Why did Korea add a higher alert in 2026?
KMA’s long comparison explains the timing. Korea averaged eight heatwave days a year in the 1970s; the 2021–2025 average was 19. Tropical nights rose from four to 14. The old two-tier system had to cover both a prolonged 35°C apparent temperature and a much more dangerous 38–39°C event (KMA 2026 summer hazard plan).
The new tier creates a clearer progression: prepare at 33°C, sharply reduce exposure at 35°C and stop at 38°C. That difference reaches beyond public health. Persistent nighttime cooling demand strains the power system. Older housing holds heat longer. Suspending construction can delay a project, but an injury can stop it for far longer.
The alert’s success cannot be measured by how often KMA sends it. The better questions are whether employers stopped dangerous work, whether cooling rooms stayed open, whether vulnerable households could afford cooling and whether severe illness fell after the warning. A louder message helps only when people have a workable way to act on it.
FAQ
- What triggers South Korea’s severe heat warning?
- An area already experiencing warning-level heat can receive the new alert when the daily maximum apparent temperature is forecast at 38°C or the air temperature at 39°C.
- What is the difference between a heat advisory and a heat warning in Korea?
- An advisory starts when a 33°C maximum apparent temperature is expected for at least two days. A warning uses 35°C for at least two days; the new severe warning adds the 38°C or 39°C extreme threshold.
- What should I do when Korea issues a severe heat warning?
- Cancel outdoor plans, move to air conditioning, drink water as medically appropriate, and check children, older adults, people with chronic conditions and outdoor workers.
- How many heat-illness cases has Korea reported in 2026?
- KDCA’s provisional emergency-room surveillance counted 1,070 patients and four suspected deaths through July 21. The network covers 516 participating hospitals and can be revised.