ichidan verb, intransitive verb
grow late; advance (of night/season)
Describes time (especially night or a season) becoming deep or advanced. Often used with 夜, 秋, etc.
夜が更けるまで話し込んだ。
We talked until late into the night.
秋が更けて、木々が色づき始めた。
As autumn deepened, the trees began to change color.