A stretch of time with its own weather and work. A season is named by what it is for.
Old French seison, from Latin sationem (a sowing, a planting-time), from serere (to sow); a season was first named for the work proper to it, the planting, before it named the weather generally.
A stretch of time known by its own weather and its own work, named for what it asks of whoever lives through it.