He says he sees things on rainy days as doesn't show when it's fair weather.

他说他在雨天看到在晴天却看不出来的东西。

Fair weather was the rule yesterday.

昨天天气普遍晴朗。

Red sky at night means fair weather.

夜里天空发红意味着晴天。

High air pressure usually means fair weather.

高气压通常意味着好天气。

Sometimes you will meet fair weather friends.

有时你会遇到不能与你共患难的朋友。