Usage Explanation ①: 暑い (Weather)

暑い (atsui) is used for weather or air temperature. It has the “Sun” (日) radical on top.

Use this when you feel hot because of the sun or the climate.

Example 1: (Summer)

日本（にほん）の夏（なつ）は、とても暑いです。(Nihon no natsu wa, totemo atsui desu.)

Japanese summer is very hot.

Example 2: (Today)

今日（きょう）は暑いですね。(Kyō wa atsui desu ne.)

It is hot today, isn’t it?

Example 3: (Room temperature)

部屋（へや）が暑いので、窓（まど）を開（あ）けました。(Heya ga atsui node, mado o akemashita.)

The room was hot, so I opened the window.

Usage Explanation ②: 熱い (Object Temperature)

熱い (atsui) is used for objects that are hot to the touch. It has the “Fire” (灬 – renga) radical at the bottom.

Use this for food, drinks, bathwater, or anything you touch. It is also used for “passionate” feelings.

Example 1: (Drink)

熱いコーヒーを飲（の）みました。(Atsui kōhī o nomimashita.)

I drank hot coffee.

Example 2: (Touch)

このお皿（さら）は熱いから、気（き）をつけてください。(Kono osara wa atsui kara, ki o tsukete kudasai.)

This plate is hot, so please be careful.

Example 3: (Bath)

お風呂（ふろ）が熱すぎます。(Ofuro ga atsu-sugimasu.)

The bath is too hot.

Usage Explanation ③: 厚い (Thickness)

厚い (atsui) means thick. It describes the dimension of an object (like paper, books, walls, coats).

It is the opposite of “thin” (usui). It has nothing to do with temperature!

Example 1: (Book)

あの厚い本（ほん）は、辞書（じしょ）です。(Ano atsui hon wa, jisho desu.)

That thick book is a dictionary.

Example 2: (Clothing)

冬（ふゆ）は、厚いコートを着（き）ます。(Fuyu wa, atsui kōto o kimasu.)

In winter, I wear a thick coat.

Example 3: (Paper/Steak)

厚い肉（にく）を食（た）べたいです。(Atsui niku o tabetai desu.)

I want to eat a thick steak (meat).

Comparison: 暑い vs 熱い vs 厚い

Check the Kanji and the opposite words!

Common Mistake Examples

Mistake 1: Weather vs. Object

Wrong:

今日（きょう）は、とても熱いですね。(Kyō wa, totemo atsui desu ne.)

Correct:

今日（きょう）は、とても暑いですね。(Kyō wa, totemo atsui desu ne.)

Why?

If you use 熱い for today, it sounds like the day itself is burning hot to the touch! For weather, use the Sun kanji: 暑い.

Mistake 2: Thick coats

Wrong:

暑いコートを買（か）いました。(Atsui kōto o kaimashita.)

Correct:

厚いコートを買（か）いました。(Atsui kōto o kaimashita.)

Why?

暑いコート means a “hot weather coat” (which is confusing). You mean a coat with “thickness,” so use 厚い.

Practice Quiz

Let’s check your understanding! Choose the correct Kanji.

Q1.

スープが ( ) から、まだ飲（の）めません。

The soup is ( ), so I can’t drink it yet.

1. 暑い
2. 熱い
3. 厚い

Q2.

教科書（きょうかしょ）が ( ) て、カバンに入（はい）りません。

The textbook is ( ), so it doesn’t fit in my bag.

1. 暑く
2. 熱く
3. 厚く

Q3.

夏（なつ）は ( ) て、冬（ふゆ）は寒（さむ）いです。

Summer is ( ) and winter is cold.

1. 暑く
2. 熱く
3. 厚く

Summary: How to Remember

It’s all about the Kanji radical!

• 暑い: Has a Sun (日). Sun = Weather hot.
• 熱い: Has a Fire (火) at the bottom. Fire = Burning object hot.
• 厚い: Has neither. It means Thick.

Mastering these three kanji is a big step for JLPT N4 and N3 reading!

Frequently Asked Questions (FAQ)

Q1: Can I use 熱い (atsui) for spicy food?

A1: No. For spicy food, we use 辛い (karai). However, if the spicy soup is physically *hot* temperature-wise, you can say it is 熱い (atsui) AND 辛い (karai).

Q2: What are the opposites of these three words?

A2: They are all different!

• 暑い (weather) ↔ 寒い (samui) (cold weather)
• 熱い (object) ↔ 冷たい (tsumetai) (cold to the touch)
• 厚い (thick) ↔ 薄い (usui) (thin)

Q3: Which one do I use for “passionate”?

A3: We use 熱い (atsui). For example, 熱い心 (atsui kokoro – a passionate heart). It relates to “fire” inside you.

Related Articles

• The Difference Between 「寒い (samui)」 and 「冷たい (tsumetai)」 (Cold)
• The Difference Between 「きれい (kirei)」 and 「美しい (utsukushii)」