遅れそう

seem likely to be late, seem likely to be delayed

→ 遅れる
遅れ be late, be delayed + そう seem/appear; reportedly
verb · potential Rare #30,600
seem likely to be late, seem likely to be delayed そう after the verb stem expresses that something appears likely to happen.
JA: 電車が遅れそうです。
EN: The train seems likely to be delayed.
Conjugation of 遅れる
Potential
遅れそう

学校に遅れそうだね

It looks like you're going to be late for school.

遅れそう

I might be late.

— アバウト・タイム ~愛おしい時間について~ (2013)

仕事に遅れそう

I’m going to be late for work.

私達遅れそうなの

Are we going to be late?

彼は遅れそうと伝えてきた

He let me know that he might be late.

遅れそうです

I think I’m going to be late.