As Nyarlonthep said, seasons differ around the world. For a couple concrete examples, the Ju/'hoansi (a !Kung San group), living in a semi-arid subtropical savanna/woodland area, divided the year into five seasons- spring rains (a time of light, scattered thundershowers), main summer rains (heavy warm-weather rains), fall (after the end of rains but before cold weather), winter (cold, dry weather), and spring (the return of hot weather but before spring rains). Obviously they have their own words for each season (things like "spring rains" are just translations). The seasons have social aspects too- during the rainy seasons, people dispersed and lived in small groups, while they aggregated around big, reliable water sources in the dry ones. Other San groups similarly divided up the year according to the local climate, though I don't know the specifics.

For more on Ju/'hoansi seasons and seasonal activities (and generally for starting learning about the Ju/'hoansi), look up Richard B. Lee's books. The !Kung San is great; The Dobe Ju/'hoansi covers most of the same ground, but more accessibly (it's meant for undergraduate courses).

A second example, at the risk of brushing against the 20-year rule (though I'm sure this nomenclature is much older than 20 years), is where I do fieldwork in Ecuador. Everyone talks about summer and winter, but no fall or spring. "Summer", at least in western Ecuador, just means the dry season, while "winter" is the wet one. At my field site in a very wet subtropical montane forest "dry" merely means that it doesn't rain every day, though in either higher altitude cloud forests or southwestern dry forests the dry season really does get dry (and in the dry forests, trees lose their leaves in the summer).