The start of spring varies depending on where you are located and which calendar system you follow. In the Northern Hemisphere, the meteorological start of spring is on March 1, while the astronomical start of spring is on March 20 or 21. This is the time when the sun is directly above the equator, and the days and nights are of equal length. In the Southern Hemisphere, the meteorological start of spring is on September 1, while the astronomical start of spring is on September 22 or 23. These dates are based on the Earth’s position in relation to the sun, and they mark the beginning of the spring season in the respective hemispheres.