The seasons are not written with capital letters, unless they form part of a name (e.g., I spent the winter near Winter Road River).|
(In the past, there was a quaint ruling which stated that you should use a capital letter for the names of the seasons when they are personified; i.e., when they are given human traits.)
Capital Letters and the SeasonsThe four seasons are not normally written with capital letters. However, if a season is given a human trait (i.e., personified), then – under an old ruling – it can be given a capital letter.
He was touched by Winter's icy breath.
(winter given a human trait - use a capital letter)
Where are you going this winter?
(no human trait - use a lowercase letter)
The leaves had been subjected to Autumn's touch.
(human trait -A is correct)
The trees were all the colours of autumn.
(no human trait -a is correct)
This is the second time I have been skiing this Winter.
(no human trait -W should be w)
DON'T WORRY ABOUT THE PERSONIFICATION RULING
Most people these days will expect you to write the seasons without capital letters regardless of personification.
If a season name forms part of a proper noun, then it is given a capital letter.
I met her at the Summer Solstice.
There were some incredible masks at the Rhine Winter Ball.