Atsui, Atatakai, Samui, Tsumetai - Meaning in Japanese

Temperature often changes in anime. One day it's freezing cold, another it's burning hot. And everyone knows "cold" is samui 寒い in Japanese, right? Or was it tsumetai 冷たい? Anyway, "warm" is atsui 暑い... I mean, atatakai 温かい... I mean atsui 熱い, or was it atatakai 暖かい? What's the difference between these words in Japanese?

There is not much of a difference. Really. Both samui and tsumetai can be translated as "cold", and both atsui and atatakai can be translated as "warm" or "hot".

The words atsui, atatakai, tsumetai and samui in Japanese (暑い, 熱い, 温かい, 暖かい, 寒い, 冷たい) and their meanings: cold, warm and hot.

Between the different words, there's small difference, but between words that are the same with difference kanji, there's only a subtle, subtle difference in meaning that can be forgotten most of the time. Much like hayai 速い and hayai 早い are slightly different but mean the same thing most of the time.

Cold and Hot Weather

The words samui 寒い and atsui 暑い are used to talk about the weather, the climate, your thermal sensation. When the the day is cold, samui is used, when the day is hot, atsui is used.

kyou wa atsui desu ne? 今日は暑いですね？
Today is hot, isn't it?
kon'ya wa samui desu ne? 今夜は寒いですね？
Tonight is cold, isn't it?

Most of the time these words are used to talk about the weather, but you can use them to talk about how you feel in a certain environment to. It's like saying "I feel cold" or "I feel warm" without saying "I feel".

Blazing Hot Weather

Some Japanese words derived from atsui 暑い are used to talk about really hot weather. These are:

mushiatsui 蒸し暑い
Very hot and humid.
atsukurushii 暑苦しい
Painfully hot!

In the last word, atsukurushii, you can see it's actually written in part with the word kurushii 苦しい which means "painful." That's just how hot the weather is.

Warm Weather

Another word, atatakai 暖かい, is used for warm weather. That is, when the weather isn't really, really hot, but it's not cold either, so it's warm. Again, you can use this word if you aren't feeling particularly cold, but then again, for some reason, you want to declare how you feel.

Cold and Warm Things

When we talk about things, and not about the weather, we have to use different kanji which have different meanings. When spoken, the words are the same, of course, you can't speak the kanji out loud after all, but when written, they are different.

Another thing is that, despite these words having different kanji, that doesn't mean Japanese people won't mistake one for the other. Much like in English you have people mistaking "you" with "your" and "it's" with "its".

Anyway, atatakai 温かい and atsui 熱い are how you say something is "warm" and "hot" respectively. To say something is "cold" in Japanese, you don't use samui 寒い but instead the word tsumetai 冷たい.

coohii wa atsui! コーヒーは熱い！
The coffee is hot!
kono mizu wa sugoku tsumetai! この水はすごく冷たい！
This water is really cold!

Warm and To Warm

An important thing to note is that these words we are talking about now are words used when something is, physically, cold, warm or hot. An extreme example:

atatakai fuku wo kaou! 暖かい服を買おう!
Let's buy warm clothes!
(so we can warm ourselves in the winter)
atatakai fuku wo kaou! 温かい服を買おう!
Let's buy warm clothes!
(so we can feel our skin burn against the heat of the fabric)

In the first example, we're buying clothes which make us feel warm. They are thick, cold-resistant, insulating clothes. In he second example, however, we are buying literally "warm" clothes. I don't know, maybe someone just ironed them, maybe the clothes were let under the sun for hours, or maybe they burn constantly with some sort of magical property.

Anyway, that's the difference between atatakai 暖かい and atatakai 温かい, and it also applies for the difference between samui and tsumetai, and the difference between atsui 熱い and atsui 暑い.

Cold and Warm Feelings

Finally, it's common in Japanese as much as it is in English to talk about cold and warm feelings. People who are cold hearted, and those who are... warm hearted. To talk about the warmth of people's actions and the coldness of their deeds.

In any case, all of the words above can be used to say this. In fact, some other readings of atsui can be used to. Take a look:

samui 寒い
tsumetai 冷たい
Cold-hearted.
atatakai 暖かい
atatakai 温かい
atsui 暑い
atsui 熱い
atsui 篤い
atsui 厚い
Warm-hearted.

Warming Up and Cooling Down

Now let's talk about change. By which I mean changing the temperature of things.

atatamaru 暖まる
To be warmed up (the weather, yourself)
atatameru 暖める
To warm up something.
atatamaru 温まる
To be warmed up (something, like after being put on the oven)
atatameru 暖める
To warm up something.
hieru 冷える
To become cold.
hiyasu 冷やす
samasu 冷ます
To cool something.

The first four words have the same nuances as the adjectives with the same kanji. Besides the words above, which are verbs, there are some phrases which also have the same meaning. All you need it throw in a naru なる to say things "will become" like something. Example:

atatakaku naru 暖かくなる
To become warm.
samuku naru 寒くなる
To become cold.
atsuku naru 熱くなる
To become hot.
tsumetaku naru 冷たくなる
To become cold.

Temperature in Japanese

One last thing, I guess I should include the words for temperature here, after all. These words are all use the kanji 温, which means warmth.

ondo 温度
Degrees of temperature. Level of temperature. Temperature.
ondokei 温度計
Thermometer.
kion 気温
Weather temperature. Air temperature.
taion 体温
Body temperature.

Japan uses celsius degrees for temperature, not fahrenheit. To say 27°C, for example, you could say nijuu nana do 27度, which would be literally "27 degrees." This do 度 counter can also be used to talk about angle degrees and so on.