What Is The First Day Of Spring 20247. The reason the first day of spring was march 19 was because 2024 is a leap year. The sun sets behind the olympic mountains as people cross a street in seattle’s alki neighborhood on the last evening of winter on monday, march 18, 2024.

The spring equinox is tuesday, march 19 and brings the first day of astronomical spring to the northern hemisphere. When is the spring equinox?