Spring begins on the March or vernal equinox, which is when the amount of sunshine is approximately 12 hours long. The amount of sunlight will incrementally increase until the first day of Summer.
The vernal equinox marks the moment the Sun crosses the celestial equator. This is the imaginary line in the sky above the Earth’s equator, from south to north. This happens on March 19, 20 or 21 every year.
The time the sun crosses the equator marking the Vernal Equinox is different for each time zone. For those in the Pacific, Mountain and Central time zones, this will occur on March 19th. For those in the Eastern time zone, spring begins on March 20th at 12:30 a.m.