Last updated: July 2026
The summer of 2025 was the hottest Korea has recorded since measurements began. The national weather service confirmed it in early 2026: a summer averaging 25.7°C, a nationwide 28.1 heatwave days — more than double the norm, and Seoul sweating through 46 tropical nights — its most ever. Add the humidity of jangma, the monsoon rains, and a typhoon or two, and your first Korean summer can feel less like weather than an opponent.
The reassuring part: Korea has spent decades building one of the world’s most complete summer-survival systems — feels-like alerts, thousands of free cooling shelters, disaster texts, cheap gear everywhere. You don’t tough it out; you learn how it works.
TL;DR
- Jangma runs late June to late July — not a month of nonstop rain, but sudden, localized downpours between clear spells.
- Heat alerts track how it feels, not just the thermometer — advisory at a 33°C feels-like, warning at 35°C, and a new top-tier critical alert for 2026.
- Your phone will scream — that’s normal. Cell-broadcast disaster texts; heat gets a routine tone, not the war-siren one. Foreign or old phone? Get the Emergency Ready App.
- Fight mold and damp laundry early — ventilate after the rain stops, use ₩1,000–2,000 moisture absorbers, dry clothes fast.
- Decode your AC remote and set it to about 26°C — and relax, summer widens the electricity pricing tiers.
- If someone’s overheating and confused, call 119 — and never pour water into an unconscious person.
What Summer Here Actually Feels Like
Korean summer arrives in two overlapping acts: the monsoon, then the heat.
Jangma (장마) is the monsoon front that stalls over the peninsula in early summer. In a normal year it reaches Jeju around June 19–July 20, the south June 23–July 24, and the central region, including Seoul, June 25–July 26 — roughly a month. But that doesn’t mean a month of rain: it actually rains on about half those days. The pattern has lately shifted from a steady front to sudden, hit-and-run cloudbursts — locals call it a dokkaebi (goblin) jangma — and in 2026 Korean meteorologists began redefining the term around seasonal atmospheric conditions rather than continuous rain, declaring its dates only in hindsight.
Once the rains lift, the heat settles in — and with it the tropical night (열대야), an overnight low that stays at or above 25°C and wrecks your sleep. Typhoons are the wildcard: of the ~25 that form over the western Pacific yearly, about 3.4 hit the Korean Peninsula annually, mostly July through October and peaking in August. And 2025 set the benchmark every new season is measured against.
Heat Alerts & Staying Safe
Korea issues heat alerts on the feels-like temperature (humidity included), a standard formally adopted in 2023 after several years of pilot testing. Two core levels: a heat advisory (폭염주의보) when the feels-like high tops 33°C for two or more days, and a heat warning (폭염경보) at 35°C. New for 2026 is a top tier — a critical heat alert (폭염중대경보) that can fire when the feels-like hits 38°C (or the air temperature 39°C) even for one day — plus a tropical-night advisory (열대야주의보) for overnight lows around 25°C, the exact threshold varying by region.
The safety rules are simple:
- Avoid the outdoors and hard labor from about 2–5 p.m., the hottest stretch.
- Drink water often — skip caffeine and alcohol, which dehydrate you.
- Wear light, loose, pale clothing.
Learn the two heat-illness patterns. Heat exhaustion leaves you conscious but drenched, dizzy, and weak — move to shade, loosen clothing, cool off, rehydrate. Heat stroke is the emergency: consciousness fades and the skin turns hot and dry because sweating has stopped. Get the person cool, wet them and fan, and put ice at the neck, armpits, and groin — but if they’re unconscious, do not give water (choking risk) and call 119 immediately. Unsure about symptoms? Our seeing a doctor guide covers getting care. And nationwide, roughly 93,000 cooling shelters — community centers, libraries, even banks — open their air-conditioning to the public (typically mid-May to end of September). They’re free, so use them.
Those Loud Phone Alerts Are Normal
Sooner or later your phone will erupt with a siren and a wall of Korean text. Don’t panic — it’s a disaster text, in three kinds:
- Safety guidance messages (안전안내문자) — heat, weather advisories, air quality. A normal alert tone. This is what heat alerts use.
- Emergency messages (긴급재난문자) — evacuations and the like, louder.
- Critical messages (위급재난문자) — reserved for war or air raids, the loudest (60dB) and impossible to switch off.
So the constant summer buzzing is almost always the routine safety kind — not the war siren. These arrive by cell broadcast, which any recent phone on a Korean SIM receives automatically (unless it’s switched off in settings), and since 2024 they increasingly carry English text alongside the Korean.
On a foreign phone or older handset and getting nothing? Install the government’s Emergency Ready App, which runs in English and other languages, and bookmark the English disaster portal at eng.safekorea.go.kr. For the numbers to call in a crisis, keep our emergency numbers guide handy.
When the Rain Really Comes
Most jangma days are just gray and wet. The danger is the localized downpour that dumps weeks of rain in hours:
- Stay out of underground roadways, underpasses, and low bridges — they flood fast and without warning.
- Keep away from streams, riversides, and mountain valleys, which can surge in minutes.
- If you live in a semi-basement (반지하), treat any water coming in as your cue to leave immediately — the scenario Korea tightened up after the deadly 2022 Seoul floods.
- If water rises around your car, abandon it for high ground rather than driving or waiting it out. Move a car from a low-lying spot before the rain, not during.
Stay clear of manholes and utility poles, too — floodwater hides live hazards.
The Mold War
Indoor humidity during jangma can climb to 70–90%, and mold takes hold above 60% — so your target is a drier 40–60%. Watch the four usual hotspots: bathroom silicone and grout, wallpaper on exterior or north-facing walls, behind wardrobes and furniture, and window frames where condensation collects.
Defense first: ventilate — but only after the rain stops (open windows mid-downpour just let moisture in), pull furniture 5–10 cm off the walls, and drop moisture absorbers (the mulmeokneun-hama tubs) into closets and shoe cabinets — about ₩1,000–2,000 each, or ₩10,000–30,000 for a multipack. When mold appears, a mold remover or diluted bleach clears it — window open.
Never mix bleach (락스) with an acidic cleaner. The combination releases toxic chlorine gas. Use one product at a time, always with ventilation.
If the mold traces to a structural cause like a leak or condensation rather than your airflow, that’s generally considered the landlord’s responsibility, while poor ventilation is the tenant’s — not legal advice, so photograph it and notify your landlord in writing as soon as you spot it. One debated local trick is running the floor-heating (boiler) briefly to dry a room; on humid days, lean on ventilation and a dehumidifier first, and save boiler-drying for after the rain passes.
Laundry That Won’t Dry
That sour smell on indoor-dried laundry is bacteria multiplying while clothes stay damp — so the whole game is drying them faster. Three moves:
- Run an extra spin cycle to wring out more water.
- Hang items with wide gaps between them.
- Point a fan or air circulator at them, ideally with a dehumidifier running.
For laundry that already smells, soak or boil it with oxygen bleach (과탄산소다). And when your place can’t dry a load, the coin laundromat (Cleantopia, Wash & Joy, others) will: a dry cycle runs roughly ₩2,000–5,000, a wash about ₩3,000–6,000.
Your AC, Decoded
Most one-rooms have a wall-mounted air conditioner with an all-Korean remote. Here’s the decoder (labels vary a little by brand):
- 냉방 = Cool (❄) · 제습 = Dry (💧) · 송풍 = Fan
- 자동 = Auto · 난방 = Heat · 취침 = Sleep · 예약 = Timer
- 풍량 = Fan speed · 온도 ▲▼ = Temperature · 회전 = Swing
Set it to about 26°C — the recommended target keeps you cool within ~5°C of outdoors, which helps you dodge “air-conditioning sickness.” Clean the filter yourself every two weeks to a month (just rinse it, no cost), and run Fan mode after cooling to dry the unit’s insides and prevent mildew smells. A professional deep-clean, usually yearly, runs about ₩60,000–90,000 for a wall unit and ₩110,000–180,000 for a floor-standing one.
Keep the outdoor unit clear of anything flammable. According to fire authorities, many air-conditioner fires start at the outdoor unit and cluster in summer, so give it 10 cm-plus of breathing room. As for leaving the AC on: for an inverter model, brief outings of an hour or two are often cheaper left running than cycled off — but that’s conditional (a fixed-speed unit is the opposite, and any long absence means switch it off), so it’s no blanket rule.
Dreading the bill? Korea’s household electricity uses progressive pricing — three tiers costing roughly ₩120, ₩215, and ₩307 per kWh (approximate) — but summer eases it: in July and August the tier boundaries widen (to 300/450 kWh from the usual 200/400), so more usage falls in the cheaper tiers, and the government adds support like discounts for vulnerable households. No AC at all? A window unit runs about ₩300,000–600,000 and a portable about ₩300,000–500,000, both self-installable.
Cooling Gear & Summer Eats
You can cool down cheaply. Daiso hand and neck fans are mostly ₩5,000; brand-name neck coolers run ₩10,000–30,000, cooling arm sleeves ₩3,000–10,000, and a cooling sleep mat about ₩20,000–50,000. At any convenience store, the summer ritual is an ice cup (around ₩1,000) topped with a pouch drink (~₩2,000). Go-to electrolyte drinks: Pocari Sweat, Toreta, Gatorade, and Lingtea. And you’ll spot parasols everywhere, carried by men and women alike — they genuinely cut the felt heat.
For sleep on a tropical night, keep the bedroom around 24–26°C at 50–60% humidity and set a 2–3 hour timer. Counterintuitively, a lukewarm shower an hour or two before bed beats a cold one, which jolts you awake.
Then the food. The boknal (복날), the “dog days,” fall on July 15, July 25, and August 14 in 2026, and tradition fights heat with heat: a bowl of samgyetang (ginseng chicken soup), roughly ₩15,000–20,000 — Seoul now averages about ₩18,000, and famous spots top ₩20,000. Round out the season with cold naengmyeon, nutty kongguksu (soybean-broth noodles), shaved-ice bingsu, and chimaek — fried chicken and beer — by the Han River at dusk.
Bug Season
Warm, damp air brings the bugs. Your first line of defense is the window screen (방충망): check for gaps and patch holes with repair tape from Daiso. Beyond that, an over-the-bed mosquito net runs about ₩10,000–20,000, an electric swatter about ₩5,000, and a plug-in vaporizer mat (machine plus refills) about ₩10,000–30,000 — just ventilate if you run one for long in a sealed room.
The other classic one-room pest is the swarm of fruit flies and drain flies breeding in your drains. Fit a drain trap or cover and keep it clean; note that leaving home for two weeks or more lets the trap’s water evaporate and the problem roar back. Sealing and often emptying your food waste cuts fruit flies off at the source — our trash & recycling guide covers doing that right.
Summer Food Safety
Heat spoils leftovers fast, so lean on the food-safety agency’s basics: wash your hands, cook food thoroughly, boil what you can, wash and disinfect produce, keep separate cutting boards and knives for raw meat, and mind storage temperatures — refrigerator below 5°C, freezer below –18°C. Cook meat to 75°C and shellfish to 85°C for a minute or more. Above all, refrigerate delivery food and leftovers immediately — never leave them out at room temperature on a hot day.
Common Problems
“There’s mold on my wall.” Photograph it and notify your landlord in writing — structural causes like leaks are generally the landlord’s side, poor ventilation the tenant’s. Then clear it with a mold remover or diluted bleach, window open, and ventilate after the rain each day.
“My laundry smells sour.” It dried too slowly. Soak or boil it with oxygen bleach (과탄산소다), then re-dry it fast — extra spin, wide spacing, a fan plus a dehumidifier — or use a coin dryer.
“My phone suddenly blared an alarm in Korean.” That’s a cell-broadcast disaster text — in summer almost always a heat or weather alert, not an emergency. Screenshot it and run it through Papago’s translator; our 12 essential apps guide covers the setup, and the Emergency Ready App shows these in English.
“I’m scared of my electricity bill.” Set the AC to about 26°C, run Fan mode to dry it between cooling sessions, and remember summer widens the pricing tiers in your favor. If yours is an inverter, leaving it on for short outings can beat switching it off — conditionally.
FAQ
Is “fan death” real? No. The belief that a fan in a closed room can kill you has no scientific basis; even in Korea it’s now an old wives’ tale. Run your fan all night — the timer is for comfort and your power bill, not survival.
Do I need an umbrella every day during jangma? Not a month of solid rain, but the downpours are sudden — so yes, carry a compact umbrella through the peak weeks.
Should I leave the AC on all the time, or switch it off? It depends. An inverter is often cheaper left running for short outings of an hour or two; a fixed-speed one isn’t, and any long absence means turn it off — no one-size answer.
Can I drink the water from my dehumidifier? Absolutely not — it’s full of bacteria and mold. Don’t drink it or pour it into a humidifier; empty it out, and use any you keep for cleaning the same day.
Can foreigners use the cooling shelters? Yes. They’re free, open-access facilities — community centers, libraries, banks — so anyone can step in during the hottest hours.
When do I tough out the heat, and when do I see a doctor? Rest, water, and shade handle mild heat exhaustion. But confusion, fainting, or hot, dry skin that isn’t sweating signal heat stroke — call 119, and don’t give an unconscious person water. For non-emergency care, see our seeing a doctor guide.
Official Resources
- Korea Meteorological Administration (English): kma.go.kr/eng — forecasts, advisories, and typhoon tracking.
- Disaster portal (English): eng.safekorea.go.kr
- Emergency Ready App: from your app store; runs in English and other languages, ideal for a foreign or older phone.
- Air quality: airkorea.or.kr
- Help lines: 1330 (24-hour tourist help line, with interpretation) and 119 (fire/ambulance, with interpreter support) — see our emergency numbers guide.
- Browse all guides