Oh, it is so confusing, even for those of us for whom English is our first language.

There is a case where a season would be capitalized and that is if it was personified. *Come, gentle Spring, with your blessed showers.* One does not capitalize the names of decades or centuries, unless they are special expressions such as the Roaring Twenties. Capitalize north, south, east, and west only when they designate a definite region, i.e. the Middle West, the Deep South, the West Coast.