열대야 (yeoldaeya) — The Korean Summer Nights That Never Cool Down
열대야
열대야 (yeoldaeya) means a very hot night — one where the outside temperature never drops below 25 degrees Celsius. From late July to mid-August in Korea, night after night the air refuses to cool down, even after the sun goes down and midnight has come and gone. You can duck into the shade to escape the daytime heat, but this heat has nowhere to hide from. Open the window and hot air blows in; close it and you can’t breathe. So at one in the morning people come out and sit on a bench in the apartment playground, or buy a single ice cream under the parasol in front of the convenience store before heading back inside.
If you’ve spent even one summer in Korea, you’re guaranteed to hear this word. News anchors use it, the lady next door uses it, and it turns up in the KakaoTalk message a friend sends you at two in the morning. It’s a meteorological term and an everyday word at the same time.
Let’s flag one nuance. 열대야 is not a human emotion — it’s the name of the night itself. That’s why it so often sits in the subject slot of a sentence: 열대야가 이어지다 (yeoldaeyaga ieojida, the tropical nights continue), 열대야가 나타나다 (yeoldaeyaga natanada, tropical nights appear). People are on the enduring side of it: 열대야에 지치다 (yeoldaeyae jichida, to be worn out by tropical nights), 열대야를 이기다 (yeoldaeyareul igida, to beat the tropical nights). Learn this structure and your sentences will sound far more natural. One more thing: the word carries a subtle warmth of shared feeling. The moment someone brings up 열대야, you both know the other person didn’t sleep last night either. That’s why it gets used almost like a summer-morning greeting.
Checking it in the National Institute of Korean Language dictionary
열대야 (yeoldaeya) 「noun」 A very hot night when the outside temperature is over 25 degrees Celsius. [en] tropical night — A very hot night when the outside temperature is over 25 degrees Celsius. [ja] ねったいや【熱帯夜】 — 室外の温度がセ氏25度以上の、非常に暑い夜。 [es] noche tropical — Noche muy calurosa con una temperatura exterior superior a los veinticinco grados centígrados. [zh] 热带夜 — 外面气温在25摄氏度以上的非常热的晚上。 — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)
The dictionary doesn’t include a Portuguese definition, so we’ve added our own translation to help you out: noite tropical — noite muito quente em que a temperatura externa fica acima de 25 graus Celsius. (our own translation)
Now let’s read through the real usage examples the dictionary gives, one at a time.
열대야가 지속되면서 밤에도 냉방기를 틀어 놓는 집이 많아서 전력 수요가 사상 최고치를 기록했다. (yeoldaeyaga jisokdoemyeonseo bame naengbanggireul teureo noneun jibi manaseo jeollyeok suyoga sasang choegochireul girokhaetda.) As the tropical nights dragged on, many households ran their air conditioners even at night, and power demand hit an all-time high. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)
This is exactly the kind of sentence you’d find in a news article. In Korea, 열대야 goes beyond personal discomfort and turns into a question of 전력 수요 (jeollyeok suyo), power demand. It’s a topic that comes back every single summer, so memorizing this sentence structure as a whole chunk will help a lot when you read current-affairs Korean.
밤에도 영상 삼십오 도를 웃도는 열대야 현상 때문에 사람들이 잠을 설쳤다. (bame yeongsang samsibo doreul utdoneun yeoldaeya hyeonsang ttaemune saramdeuri jameul seolchyeotda.) Because of tropical nights that stayed above 35 degrees Celsius even after dark, people slept badly. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)
잠을 설치다 (jameul seolchida) shows up here. It means you couldn’t sleep soundly and kept waking up — an expression that travels with 열대야 almost as one body. Also keep an eye on the form 열대야 현상 (yeoldaeya hyeonsang). In the news and in written Korean, people attach 현상 (phenomenon) to make it sound a bit more formal.
한여름에는 밤에도 무더운 열대야 현상이 나타난다. (hanyeoreumeneun bame mudeoun yeoldaeya hyeonsangi natananda.) In midsummer, sweltering tropical nights appear even after dark. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)
Here it’s paired with 한여름 (hanyeoreum), the time expression for the very middle of summer. Tropical nights don’t show up in just any season, and this sentence lays out that timing condition precisely.
열대야에 지치다. / 열대야를 이기다. / 열대야가 이어지다. (yeoldaeyae jichida. / yeoldaeyareul igida. / yeoldaeyaga ieojida.) To be worn out by tropical nights. / To beat the tropical nights. / The tropical nights continue. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)
Short, but the three most practical chunks here. In the first two, a person is the subject (지치다 · 이기다); in the last one, the night is the subject (이어지다). Remember that the particle changes accordingly — 에 / 를 / 가 — and you won’t slip up.
See it in a real conversation
Situation: 1 a.m., the playground of an apartment complex. Two people who can’t fall asleep happen to run into each other on a bench.
Jun-kyung: 어? 에밀리 너도 못 자? Huh? You couldn’t sleep either?
Emily: 아, 진짜… 방에 있으면 숨이 턱 막혀. 이게 말로만 듣던 열대야구나. Ugh, seriously… I can’t breathe in my room. So this is the tropical night everyone talks about.
Jun-kyung: 오늘 밤 최저기온이 이십팔 도래. 이 정도면 선풍기는 그냥 뜨거운 바람 나오는 기계야. They said tonight’s low is 28 degrees. At this point the fan is just a hot-air machine.
Emily: 캐나다에선 여름에도 밤엔 이불 덮고 잤거든. 여기 와서 열대야에 지친다는 말이 뭔지 알았어. Back in Canada I slept under a blanket even in summer. Only here did I learn what it means to be worn out by tropical nights.
Jun-kyung: 에어컨 켜면 되잖아. Just turn on the AC then.
Emily: 지난달 전기요금 보고 손이 안 올라가. After seeing last month’s electricity bill, my hand won’t move.
Jun-kyung: 인정. 나도 그래서 나왔어. 편의점 가서 아이스크림 하나씩 먹고 들어가자. Fair. That’s why I came out too. Let’s grab an ice cream at the convenience store and head back in.
Emily: 콜. 이러다 우리 열대야 끝날 때까지 매일 새벽에 만나겠다. Deal. At this rate we’ll be meeting here at dawn every day until the tropical nights are over.
Jun-kyung: 그것도 나쁘지 않은데? That wouldn’t be so bad, actually.
Used this way, it sounds off
✗ 오늘 낮에 진짜 열대야라서 밖에 못 나갔어. (oneul naje jinjja yeoldaeyaraseo bakke mot nagasseo. — It was such a tropical night this afternoon that I couldn’t go outside.)
✓ 오늘 낮에 진짜 폭염이라서 밖에 못 나갔어. (oneul naje jinjja pogyeomiraseo bakke mot nagasseo. — It was such a heat wave this afternoon that I couldn’t go outside.)
→ The 야 (夜) in 열대야 means night. You never use it for daytime heat. Daytime is 폭염 (pogyeom) or 무더위 (mudeowi). This is the mistake learners make most often, and Korean speakers hear it as odd immediately.
✗ (on a spring night, 19 degrees) 어제 좀 더웠지? 완전 열대야였어. (eoje jom deowotji? wanjeon yeoldaeyayeosseo. — It was a bit hot yesterday, right? Total tropical night.)
✓ (on a spring night, 19 degrees) 어제 좀 더웠지? 좀 후텁지근했어. (eoje jom deowotji? jom huteopjigeunhaesseo. — It was a bit hot yesterday, right? Kind of muggy.)
→ 열대야 is a weather term with a fixed 25-degree threshold. Use it for a merely slightly warm night and it sounds like an exaggeration, so people will take it as a joke. For a night that doesn’t meet the threshold, say 후텁지근하다 (huteopjigeunhada) or just 좀 덥다 (jom deopda), it’s a bit hot.
Example sentences by situation
1. On your way to work, running into a neighbor in the elevator
열대야가 벌써 일주일째네요. 밤에 좀 주무셨어요? (yeoldaeyaga beolsseo iljuiljjaeneyo. bame jom jumusyeosseoyo?) That’s a week of tropical nights already. Did you get any sleep last night?
On a Korean summer morning, the weather is the greeting. Nothing fills an awkward silence better, and since the other person obviously didn’t sleep either, sympathy flows right away. Counting how many days it’s been running is also a very Korean way of talking about it.
2. When a coworker yawns at the office
어제 열대야 때문에 한숨도 못 잤어요. 커피 없으면 오늘 못 버틸 것 같아요. (eoje yeoldaeya ttaemune hansumdo mot jasseoyo. keopi eopseumyeon oneul mot beotil geot gatayo.) I didn’t sleep a wink last night because of the tropical night. I don’t think I’ll survive today without coffee.
한숨도 못 자다 (hansumdo mot jada) is an exaggerated way to say you didn’t sleep for even a moment. It pairs with 열대야 constantly, so learn it as one chunk.
3. A late-night message to a friend
이 열대야 언제 끝나냐… 나 진짜 지쳤어. 자냐? (i yeoldaeya eonje kkeutnanya… na jinjja jichyeosseo. janya?) When is this tropical night going to end… I’m seriously exhausted. You asleep?
It’s casual speech (반말) and the sentences are short. It’s a message from someone lying awake in the small hours to a friend in the same boat — and if a reply comes back, that means they’re not sleeping either.
Formal and casual speech, and similar expressions
열대야 is a noun, so there’s no honorific level built into the word itself. You adjust politeness through the predicate that follows — 열대야가 이어지고 있습니다 (yeoldaeyaga ieojigo itseumnida), the tropical nights are continuing (news, formal) / 열대야 장난 아니다 (yeoldaeya jangnan anida), these tropical nights are no joke (between friends). In other words, you can use this word in a conference room and at a drinking table alike. It’s one of the few summer words that doesn’t care where you are.
| Expression | Temperature · intensity | Where it’s used |
|---|---|---|
| 열대야 (yeoldaeya) | Clear threshold (25 degrees), nights only | News and everyday talk alike. Works with anyone |
| 폭염 (pogyeom) | Strongest and most official. Daytime heat | News, emergency alerts, weather forecasts |
| 무더위 (mudeowi) | Humid, stifling heat. Neutral | Day or night. Written and spoken |
| 찜통더위 (jjimtongdeowi) | Exaggerated metaphor (like being inside a steamer) | Friendly conversation, article headlines |
| 후텁지근하다 (huteopjigeunhada) | An adjective. The mildest of the bunch | Anywhere. A light complaint |
In one line: daytime is 폭염, nighttime is 열대야, add humidity and it’s 무더위, when you feel like you’re dying it’s 찜통더위, and when it’s just kind of warm it’s 후텁지근하다.
Cultural background — the people who come outside and sit
열대야 is a Sino-Korean word. 열대 (熱帶) refers to the tropics, the hot belt of the earth, and 야 (夜) means night. Literally, it means a night like a night in the tropics. Korea isn’t in the tropics, yet its midsummer nights refuse to cool down as if it were — so the name carries a faint note of grievance.
In weather observation, a night counts as a 열대야 when the overnight low never falls below 25 degrees Celsius. That’s why every summer the Korean news reports the numbers: how many consecutive days of tropical nights we’re on this year, and how many years it’s been since the last record. People are unusually sensitive to that day count for a simple reason — the number is also the number of nights they haven’t slept.
These nights have created a whole Korean summer landscape. Past midnight, the parks along the Han River fill up with people sitting on picnic mats, and every parasol table in front of the convenience stores is taken. Apartment playground benches, 24-hour cafés, and the neighborhood fried-chicken place stay busy until dawn. You might ask why they don’t just turn on the air conditioning — but anyone who has received a single summer electricity bill never asks that question twice.
In Korean dramas too, almost no summer-set story is complete without a scene of a sleepless character sitting out on a rooftop or a wooden platform. It’s night, yet they’re fanning themselves, and somebody comes up carrying a plate of watermelon. In storytelling, 열대야 works as a device that pulls people out of the house — because there’s no better night for two people who can’t sleep to run into each other by chance. That’s exactly why we put Jun-kyung and Emily on a playground bench at one in the morning in the dialogue above.
So learning this word isn’t just memorizing one more weather expression. It’s learning how Koreans endure summer nights — and how they confirm that endurance to each other. Next summer, when someone brings up last night’s 열대야 over morning coffee, that’s not a conversation about the weather. It’s a greeting that means you didn’t sleep either, did you.
Today’s quiz
Which of the following uses 열대야 naturally?
- 오늘 낮에 열대야라서 아스팔트가 녹을 것 같았어요. (It was a tropical night this afternoon, so the asphalt looked like it was going to melt.)
- 열대야가 일주일째 이어져서 다들 잠을 설치고 있어요. (The tropical nights have gone on for a week, so everyone is sleeping badly.)
- 어제 그 사람 표정이 아주 열대야였어요. (That person’s expression yesterday was very tropical night.)
- 겨울인데 방 안이 더워서 완전 열대야네요. (It’s winter, but the room is hot, so it’s a total tropical night.)
Show the answer
Answer: 2
Number 1 is wrong because it’s used for the daytime — daytime heat is 폭염. Number 3 applies it to a person’s facial expression, but 열대야 is the name of a night, not a word that describes someone’s state. Number 4 is set in winter, and indoors on top of that; 열대야 is measured by the outside temperature, so it doesn’t apply to an overheated room. In number 2, the night is the subject and the predicate is 이어지다 — exactly the same structure as the dictionary example sentences.
Definitions and example sentences are from the National Institute of Korean Language’s Basic Korean Dictionary (krdict.korean.go.kr); that portion of this post, including our translations, is licensed under CC BY-SA 2.0 KR.