天公作美

tiān gōng zuò měi

the weather plays along

Character by character

天tiān
heaven

公gōng
lord

作zuò
make

美měi
fine

天公作美，运动会那天是个大晴天。

The weather played along: sports day was bright and sunny.

Tone: positive (praise).

Often negated when it rains on your plans: 天公不作美.

Learn it in context

This idiom and thousands more are in Learn Chinese with Bao, with audio, pinyin and drills that make them stick.