Hello, I’m Kodak.
On a summer day in Japan, one of the first Japanese reactions you will hear is:
Atsui!
It’s hot!
暑い (atsui) means that the weather, air, season, or room feels hot.
For a hot drink, hot food, or a hot object, Japanese normally uses a different kanji: 熱い.
暑い (atsui) means “hot” when talking about the weather, climate, air temperature, a season, or a place that feels hot.
今日は暑いです。
Kyō wa atsui desu.
It is hot today.
In this article, you will learn:
② how to pronounce and write it
③ how to use and conjugate it as an い-adjective
④ the important difference between 暑い and 熱い
⑤ how it differs from 暖かい, 蒸し暑い, 暑苦しい, and 涼しい
⑥ how Japanese people talk about summer heat
⑦ natural example sentences, conversations, anime usage, and FAQ
What Does 暑い (Atsui) Mean?
暑い describes air temperature that feels high. It is used for weather, seasons, days, nights, rooms, and other environments.
⇒ hot
⇒ warm or hotter than expected, depending on context
⇒ uncomfortably hot
⇒ used for weather, air, climate, seasons, and places
今日は暑い。
Kyō wa atsui.
It is hot today.
この部屋は暑い。
Kono heya wa atsui.
This room is hot.
日本の夏は暑い。
Nihon no natsu wa atsui.
Summer in Japan is hot.
For example, 五月にしては暑い can be translated as “It’s warm for May.”
The surrounding air temperature is high enough that your body feels the heat.
How to Pronounce 暑い
Hiragana: あつい
Romaji: atsui
Mora: あ・つ・い (3 morae)
Break the pronunciation into three short Japanese beats:
An open “ah” sound.
つ (tsu)
A compact “tsu” sound. Keep the t and s together.
い (i)
A short “ee” sound.
Think of three even beats: a-tsu-i. Do not turn it into two beats, and do not drop the tsu.
Kanji, Hiragana, and Katakana Forms
All hiragana: あつい
Katakana for emphasis: アツイ
The normal spelling is 暑い. The kanji 暑 is associated with heat in the weather or climate.
Katakana アツイ may appear in advertisements, manga, social media, or stylized writing, but ordinary sentences normally use 暑い.
暑い → 暑くない → 暑かった → 暑くて
How to Use 暑い
暑い is an い-adjective. You can place it before a noun or use it at the end of a sentence.
1. 暑い + Noun
a hot day
暑い夏
a hot summer
暑い夜
a hot night
暑い部屋
a hot room
暑い地域
a hot region
暑い日が続いている。
Atsui hi ga tsuzuite iru.
The hot days are continuing.
2. ～は暑い
今日は暑いです。
Kyō wa atsui desu.
It is hot today.
八月の東京は暑い。
Hachigatsu no Tōkyō wa atsui.
Tokyo is hot in August.
3. 暑くて～
Change 暑い to 暑くて when connecting the heat to another result.
↓ remove い
暑
＋ くて
暑くて
暑くて眠れない。
Atsukute nemurenai.
It is so hot that I cannot sleep.
外は暑くて、長く歩けなかった。
Soto wa atsukute, nagaku arukenakatta.
It was hot outside, so I could not walk for long.
4. 暑かった
昨日は本当に暑かった。
Kinō wa hontō ni atsukatta.
Yesterday was really hot.
5. 暑くない
今日はそれほど暑くない。
Kyō wa sorehodo atsukunai.
It is not that hot today.
6. 暑くなってきた
This very common phrase means that the weather is beginning to feel hotter.
だんだん暑くなってきた。
Dandan atsuku natte kita.
It is gradually getting hotter.
Useful Conjugations
暑くない — is not hot
暑かった — was hot
暑くなかった — was not hot
暑くて — hot, so / hot and
暑ければ — if it is hot
暑さ — heat; degree of hotness
暑くなる — become hot
The adjective itself still carries the tense or negative form:
暑かったです, 暑くないです, and 暑くなかったです.
How to Say “It’s Hot” Naturally in Japanese
The shortest and most natural reaction is simply:
It’s hot!
Japanese often omits “it is,” “today,” and the subject because the situation is obvious.
It’s hot!
暑いね。
It’s hot, isn’t it?
今日も暑いですね。
It’s hot again today, isn’t it?
すごく暑い。
It’s very hot.
暑すぎる。
It’s too hot.
暑くなってきたね。
It’s getting hotter, isn’t it?
暑い vs 熱い: The Most Important Difference
Both words are pronounced atsui, but they use different kanji and describe different kinds of heat.
Hot weather, air, season, or room
⇒ environmental heat
熱い
A hot object, food, drink, liquid, surface, or body temperature
⇒ something contains or gives off heat
Am I describing the surrounding air, or a specific thing?
Air and weather ⇒ 暑い
A thing you can touch, eat, drink, or measure as heated ⇒ 熱い
今日は暑い。
It is hot today.
⇒ The surrounding air feels hot.
このお茶は熱い。
This tea is hot.
⇒ The drink itself has a high temperature.
部屋が暑い。
The room is hot.
⇒ The air in the room feels hot.
床が熱い。
The floor is hot.
⇒ The surface itself is hot to the touch.
お風呂が熱い。
The bathwater is hot.
⇒ The water itself has a high temperature.
If the body itself feels unusually warm—such as with a fever—体が熱い may be appropriate. Context matters.
暑い vs 暖かい: Hot or Warm?
comfortably warm; mild; pleasantly not cold
暑い (atsui)
hot enough to be strongly felt, often uncomfortable
今日は暖かい。
Kyō wa atatakai.
It is warm today.
今日は暑い。
Kyō wa atsui.
It is hot today.
暖かい usually feels pleasant or gentle. 暑い means the heat is strong enough that you clearly notice it, often with discomfort.
Spring came, and it became pleasantly warmer.
昼になると暑くなった。
By noon, it became hot.
暑い vs 蒸し暑い
暑い does not tell us whether the air is dry or humid. 蒸し暑い specifically combines heat with humidity.
hot; focuses on high air temperature
蒸し暑い
hot and humid; muggy; the air feels heavy and moist
砂漠は暑い。
Sabaku wa atsui.
The desert is hot.
雨上がりは蒸し暑い。
Ameagari wa mushiatsui.
It is hot and humid after the rain.
Use 蒸し暑い when you specifically want to include the muggy, humid feeling.
暑い vs 暑苦しい
暑苦しい describes something that feels or looks oppressively hot, heavy, crowded, or unsuitable for warm weather.
The air or weather is hot.
暑苦しい
Something creates an oppressive impression of heat.
It can describe clothes, appearance, atmosphere, or a crowded space.
今日は暑い。
It is hot today.
夏にその厚い服は暑苦しく見える。
That thick outfit looks uncomfortably hot in summer.
A person’s clothing or appearance can look 暑苦しい, but calling the person 暑い人 does not usually mean “a hot person” in the English sense.
暑い vs 涼しい
hot
涼しい (suzushii)
cool and refreshing; pleasantly not hot
昼は暑いけど、夜は涼しい。
Hiru wa atsui kedo, yoru wa suzushii.
It is hot during the day, but cool at night.
For genuinely cold weather, Japanese uses 寒い.
How Japanese People Talk About Summer Heat
Japanese summer conversations often begin with the weather. Saying 暑いですね is not only a factual statement—it can also function as easy small talk.
It’s hot, isn’t it?
毎日暑いですね。
It’s hot every day, isn’t it?
今年の夏は暑いですね。
This summer is hot, isn’t it?
暑さが厳しいですね。
The heat is severe, isn’t it?
暑い日が続きますね。
These hot days just keep coming, don’t they?
本当ですね。 — It really is.
暑いですね。 — Yes, it’s hot.
本当に暑いです。 — It’s really hot.
What Is Summer in Japan Like?
Japan has large regional differences, from subarctic northern areas to subtropical southern islands. Still, eastern and western Japan are commonly described as having hot and humid summers, while northern Japan is generally cooler.
The first half of summer is influenced by the rainy season in most areas outside Hokkaido. Later in summer, high pressure often brings sunny, hot weather across the country.
日本の夏は暑い。
Summer in Japan is hot.
日本の夏は暑くて湿度が高い。
Japanese summers are hot and humid.
地域によって気候が違う。
The climate differs by region.
北海道の夏は本州より涼しいことが多い。
Summers in Hokkaido are often cooler than in Honshu.
夏の後半は暑い日が多い。
There are many hot days in the latter half of summer.
Avoid treating “Japan’s summer” as one identical climate. 暑い is common, but local conditions vary.
Japanese Weather Terms for Hot Days
Japanese weather reports use specific terms based on the day’s maximum temperature.
A day with a maximum temperature of 25°C or higher.
真夏日 (manatsubi)
A day with a maximum temperature of 30°C or higher.
猛暑日 (mōshobi)
A day with a maximum temperature of 35°C or higher.
熱帯夜 (nettaiya)
A night when the minimum temperature from evening to the following morning is 25°C or higher.
Useful Expressions Built from 暑い
heat; degree of hotness
暑がる (atsugaru)
to show or say that one feels hot
暑がり (atsugari)
a person who is sensitive to heat
暑すぎる (atsusugiru)
to be too hot
暑くなる (atsuku naru)
to become hot
暑さに弱い (atsusa ni yowai)
to be bad at handling heat
暑さに慣れる (atsusa ni nareru)
to get used to the heat
暑さをしのぐ (atsusa o shinogu)
to escape or endure the heat
暑がる describes another person showing signs of feeling hot.
私は暑い。
I feel hot.
子どもが暑がっている。
The child is showing that they feel hot.
Conversation Examples
Weather Small Talk
Kyō mo atsui desu ne.
It’s hot again today, isn’t it?
B: 本当ですね。外に出たくないです。
Hontō desu ne. Soto ni detakunai desu.
It really is. I don’t want to go outside.
Turning on the Air Conditioner
Kono heya, atsukunai?
Isn’t this room hot?
B: うん。エアコンをつけよう。
Un. Eakon o tsukeyō.
Yeah. Let’s turn on the air conditioner.
Talking About Japan
Nihon no natsu wa dō?
What is summer in Japan like?
B: 地域によるけど、東京はかなり暑いよ。
Chiiki ni yoru kedo, Tōkyō wa kanari atsui yo.
It depends on the region, but Tokyo is quite hot.
A Hot Night
Kinō, nemureta?
Were you able to sleep yesterday?
B: あまり眠れなかった。夜も暑かったから。
Amari nemurenakatta. Yoru mo atsukatta kara.
Not really. It was hot even at night.
Natural Example Sentences with 暑い
今日は朝から暑い。
Kyō wa asa kara atsui.
It has been hot since this morning.
外はとても暑いです。
Soto wa totemo atsui desu.
It is very hot outside.
暑いから、水をたくさん飲んでね。
Atsui kara, mizu o takusan nonde ne.
It is hot, so drink plenty of water.
今年の夏は去年より暑い。
Kotoshi no natsu wa kyonen yori atsui.
This summer is hotter than last summer.
昼になると急に暑くなった。
Hiru ni naru to kyū ni atsuku natta.
It suddenly became hot around noon.
暑くて窓を開けた。
Atsukute mado o aketa.
It was hot, so I opened the window.
今日は昨日ほど暑くない。
Kyō wa kinō hodo atsukunai.
Today is not as hot as yesterday.
この暑さにはまだ慣れていない。
Kono atsusa ni wa mada narete inai.
I am not used to this heat yet.
八月は暑い日が多い。
Hachigatsu wa atsui hi ga ōi.
There are many hot days in August.
部屋が暑すぎて集中できない。
Heya ga atsusugite shūchū dekinai.
The room is too hot for me to concentrate.
日なたは暑いけど、木陰は涼しい。
Hinata wa atsui kedo, kokage wa suzushii.
It is hot in the sun, but cool in the shade.
暑い日は冷たい麺が食べたくなる。
Atsui hi wa tsumetai men ga tabetaku naru.
On hot days, I start wanting cold noodles.
まだ六月なのに暑い。
Mada rokugatsu na noni atsui.
It is hot even though it is only June.
今日は風があるから、あまり暑く感じない。
Kyō wa kaze ga aru kara, amari atsuku kanjinai.
Because there is a breeze today, it does not feel very hot.
夜になっても暑さが残っている。
Yoru ni natte mo atsusa ga nokotte iru.
The heat remains even after night falls.
How 暑い Is Used in Anime, Manga, and Casual Speech
暑い is ordinary everyday Japanese, so it appears constantly in anime, manga, games, and dramas.
It’s hot!
暑すぎる！
It’s way too hot!
あー、暑い。
Ugh, it’s hot.
こんな暑い日に外へ行くの？
You’re going outside on a hot day like this?
暑くてやる気が出ない。
It’s so hot that I have no motivation.
あっつい！ stretches and strengthens the reaction: “It’s sooo hot!”
暑っ！ is a clipped exclamation: “Hot!”
Use standard 暑い first, and learn these mainly for recognition.
Origin and History of 暑い
The modern adjective 暑い comes from the older form あつし (atsushi). Japanese dictionaries explain that 暑い and 熱い share the same linguistic origin.
In modern writing, the kanji help separate the two main meanings:
high air temperature; hot weather or environment
熱い
a heated object, liquid, food, surface, body, feeling, or enthusiasm
Think of them as one old heat concept that is now divided by context in writing.
Common Beginner Mistakes
Mistake 1: Writing 暑い for Hot Food or Drinks
○ 熱いコーヒー
hot coffee
× 暑いスープ
○ 熱いスープ
hot soup
Mistake 2: Using 熱い for Weather
○ 今日は暑い。
It is hot today.
Mistake 3: Saying 私は暑い Too Often
私は暑い is grammatical in the right context, but Japanese usually omits the subject. Simply saying 暑い is often more natural.
Mistake 4: Assuming 暑い Always Means Extreme Heat
The strength depends on context and modifiers.
a little hot
かなり暑い
quite hot
とても暑い
very hot
ものすごく暑い
extremely hot
暑すぎる
too hot
Mistake 5: Treating Japan as One Climate
Japan’s climate differs significantly by latitude, coast, elevation, and region. Use broad descriptions such as “much of Japan” rather than assuming every place has the same summer.
FAQ About 暑い
What does atsui mean in Japanese?
暑い (atsui) means “hot” when describing weather, air temperature, a season, a room, or another environment.
How do you write atsui in Japanese?
For hot weather or air, write 暑い. The hiragana form is あつい.
How do you say “It’s hot” in Japanese?
Simply say 暑い. A polite sentence is 今日は暑いです, meaning “It is hot today.”
What is the difference between 暑い and 熱い?
暑い describes hot weather, air, seasons, and rooms. 熱い describes hot objects, drinks, food, water, surfaces, and other things that physically contain heat.
Is 暑い an い-adjective?
Yes. Its common forms include 暑くない, 暑かった, 暑くなかった, and 暑くて.
Can 暑い describe a room?
Yes. この部屋は暑い means “This room is hot,” referring to the air or environment inside it.
Can 暑い mean “warm”?
Depending on context, English may translate it as “warm,” especially when the weather is hotter than expected but not intensely hot. However, 暖かい usually means pleasantly warm.
What is the difference between 暑い and 蒸し暑い?
暑い means “hot.” 蒸し暑い means “hot and humid” or “muggy.”
How do you say “too hot” in Japanese?
Say 暑すぎる. The polite form is 暑すぎます.
What is the opposite of 暑い?
涼しい means pleasantly cool, while 寒い means cold.
Does atsui always use the kanji 暑?
No. The pronunciation atsui is also written 熱い when describing a hot object, liquid, food, body, or an intense feeling.
How hot is summer in Japan?
Conditions vary greatly by region. The Japan Meteorological Agency describes eastern Japan as having hot and humid summers and western Japan as having very hot and humid summers, while northern Japan is generally cooler.
Related Japanese Summer and Heat Vocabulary
蒸し暑い (mushiatsui) — hot and humid; muggy
猛暑 (mōsho) — intense heat; extremely hot weather
酷暑 (kokusho) — severe or cruel heat
真夏 (manatsu) — midsummer
夏日 (natsubi) — a day with a high of at least 25°C
真夏日 (manatsubi) — a day with a high of at least 30°C
猛暑日 (mōshobi) — a day with a high of at least 35°C
熱帯夜 (nettaiya) — a night whose minimum temperature remains at least 25°C
日差し (hizashi) — sunlight; rays of the sun
炎天下 (entenka) — under the blazing sun
涼しい (suzushii) — cool and refreshing
夏バテ (natsubate) — summer fatigue
暑い ⇒ hot weather or air
熱い ⇒ a hot object, drink, or food
蒸し暑い ⇒ hot and humid
Those three solve most beginner problems with Japanese “hot.”
Summary: The Meaning and Usage of 暑い
暑い means “hot” for weather, air temperature, seasons, rooms, and environments.
● Writing
Kanji: 暑い
Hiragana: あつい
Romaji: atsui
● Core image
The surrounding air temperature is high enough that your body feels the heat.
● Grammar
It is an い-adjective:
暑くない / 暑かった / 暑くて / 暑ければ
● Most important distinction
暑い = hot weather, air, or room
熱い = a hot object, drink, food, liquid, or surface
● Related words
暖かい = pleasantly warm
蒸し暑い = hot and humid
暑苦しい = oppressively hot-looking or hot-feeling
涼しい = pleasantly cool
● Natural reaction
暑い！ = It’s hot!
The air is hot ⇒ 暑い
The thing is hot ⇒ 熱い
Once that distinction feels natural, Japanese summer conversations become much easier!
References
- Kotobank: 暑い — dictionary meaning, grammar, related words, and the shared origin of 暑い and 熱い.
- Kotobank Progressive Japanese–English Dictionary: 暑い — English translations and examples such as hot, warm, scorching, and sweltering.
- Japan Meteorological Agency: General Information on Climate of Japan — regional differences in Japan’s summer climate.
- Japan Meteorological Agency: Overview of Japan’s Seasonal Weather — rainy-season influence and hot weather during the latter half of summer.
- Japan Meteorological Agency: Temperature FAQ — definitions of 夏日, 真夏日, 猛暑日, and 熱帯夜.
- Japan National Tourism Organization: Summer in Japan — overview of hot and humid weather across much of Japan.