First Day Of Spring 20243. Although the vernal equinox is often referred to as the “first day of spring,” there are different ways to define the season. In the northern hemisphere, the march equinox (or spring equinox) determines the first day of spring—and this year, it falls on march 19.
What is the spring equinox and what happens on this day? The first day of spring, also known as spring equinox or vernal equinox, has traditionally been celebrated either on march 20 or march 21.