noun
depending on the weather
Used to express that something is conditional on weather conditions. Often appears in phrases like 天気次第で or 天気次第だ.
明日のピクニックは天気次第です。
Tomorrow's picnic depends on the weather.
試合の開催は天気次第だ。
Whether the match is held depends on the weather.
次第 is a suffix meaning 'depending on' or 'as soon as'. 天気次第 is a specific compound using this suffix.
Compound of 天気 (weather) and 次第 (depending on).