Spring And Fall Equinox 2025. When is it, and what is it? As you can see, the warm seasons, spring and summer, combined are 7.584 days longer than the colder seasons, fall and winter (good news for warm weather admirers!).

As you can see, the warm seasons, spring and summer, combined are 7.584 days longer than the colder seasons, fall and winter (good news for warm weather admirers!). An equinox is one of two days in the year when the sun crosses the equator and day and night become equal in length.