Thursday is the first day of spring, or the vernal equinox, in the Northern Hemisphere. During an equinox, the center of the sun is on the same plane as the equator. After the vernal equinox in March, the Northern Hemisphere tilts toward the sun until the June solstice, when the sun begins to migrate back south.

April showers may bring May flowers, but the start of spring comes even earlier — in March. The Earth is experiencing its vernal equinox on March 20. While it may not immediately transition into warm weather across the entire Northern Hemisphere,