How to Say "Late at Night" in Japanese

夜遅くに

yoru osoku ni

The Japanese phrase for "late at night" is 夜遅くに (yoru osoku ni).

夜遅くに is used to describe something that happens during the final hours of the night before the morning.

What does it mean word for word?

The phrase is composed of 夜 (yoru, night), 遅く (osoku, late/slowly) and に (ni, at/in).

The particle に can be omitted in casual speech or when the phrase functions as an adverbial modifier without a specific emphasis on the time point.

yoru osoku ni

When discussing the time around midnight, Japanese people often use the term 日付が変わる (hizuke ga kawaru), which literally means 'the date changes'. This is a common way to mark the transition from one day to the next during the late night hours.
The adverbial form 遅く (osoku) comes from the adjective 遅い (osoi). While this is the standard way to say 'late' regarding time, it is also the word used to describe something that is 'slow' in speed, creating a linguistic link between temporal lateness and physical slowness.
The concept of 'late at night' is often associated with the word 夜更かし (yofukashi), which specifically means the act of staying up late or 'burning the midnight oil'.

私は夜遅くに寝ます。
I go to bed late at night.
This sentence shows how to use 夜遅くに to describe a regular nighttime habit.
Tatoeba #158625 by bunbuku, translation #255903 by CK
その事故は夜遅くに起こった。
The accident happened late at night.
This sentence illustrates using 夜遅くに to describe when an event occurred.
Tatoeba #209817 by bunbuku, translation #47080 by CK
こんな夜遅くに電話してごめんね。
I'm sorry to call you so late at night.
This sentence shows how to use 夜遅くに when apologizing for the timing of a contact.
Tatoeba #3024534 by tommy_san, translation #3052451 by WestofEden
6 more sentences on Tatoeba

Ren is visiting Misaki's house unexpectedly.

蓮 Ren

夜遅くにすみません。
Yoru osoku ni sumimasen.
I'm sorry for coming so late at night.
美咲 Misaki

大丈夫ですよ。どうしたの？
Daijōbu desu yo. Dō shita no?
It's okay. What happened?
蓮 Ren

夜遅くに相談したくて来ました。
Yoru osoku ni sōdan shitakute kimashita.
I came because I wanted to talk to you late at night.
美咲 Misaki

いいですよ。中に入ってください。
Ii desu yo. Naka ni haitte kudasai.
That's fine. Please come inside.

Sources

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