The calculated dates and times are astronomical. Your official calendar seasons are subject to local regulation.
season [all|spring|summer|autumn|winter] year
$ git clone https://github.com/4nickel/season
$ cd season
$ make
Find the binary in bin
and copy it to your $PATH
:
$ cp bin/season ~/.local/bin
$ season spring 2019
2019-03-20@21:57