With spring upon us I have been finding myself typing out the names of the seasons a lot and found it quite confusing sometimes on the subject of to capitalize or not so I hope that this helps to clear things up for you if you have trouble with that too.
Generally, when you are using the name of a season as a noun or adjective, it shouldn't be capitalized. However, there are times when seasons are capitalized including when they're used as proper nouns, when they start a sentence, when they're used in titles, or when they're personified. The same applies for springtime, summertime and wintertime when they are used as nouns in a sentence.
Seasons as a Noun
For example, "In Japan it is very muggy in summer and cold in winter." In this case summer and winter are not capitalized because they are used as nouns.
Seasons as a Proper Noun
A season should be capitalized when it is being use as part of a proper noun as in Spring break. A proper noun describes a particular thing, place, or person. For example, "In Japan, the Spring break starts with the end of the academic year in March and ends on April first with the beginning of a new academic year."
Seasons at the Beginning of Sentences
As with normal sentence capitalization rules, the name of a season has to be capitalized when it's at the beginning of a sentence. For example, "Winter is my favorite season of the year because I can go snowboarding!"
Seasons Used in Titles
When the name of a season is used in a title, it should be capitalized. For example, "Boys of Summer was a great tune!"
In poetry and other literature, personification is giving an inanimate object, animal, or abstract notion the qualities and attributes of a human being. It is like you are making that "thing" alive. When a season is used this way, it should be capitalized. For example, "I wonder if 'tis Summer's pleasure, making us sweat and gasp for air in her fiery muggy days."
I hope this helps clear things up or at least make it a bit easier to know when to capitalize or not.