First Day Of Spring 2024 Usa 2024. This is also the start of the vernal equinox. The length of the day will be about the same all over the world โ.
But why does the day mark the start of spring and why only in the northern hemisphere? The first day of spring (march equinox or vernal equinox) is when the sun shines directly on the celestial equator passing from south to north and the length of day and night.