noun
weather of the four seasons
Refers to the characteristic weather of each season: spring warmth, summer heat, autumn coolness, and winter cold. A somewhat literary or traditional term.
この土地は四気がはっきりしている。
This region has clearly distinct seasonal weather.
四季 refers to the four seasons themselves, while 四気 refers specifically to the weather or atmospheric conditions associated with each season.
Compound of 四 (four) and 気 (atmosphere, energy, spirit). The exact historical derivation is uncertain, but the term is conventionally associated with the four seasonal weather patterns.