In the Northern Hemisphere, the March equinox (aka spring equinox or vernal equinox) occurs when the Sun crosses the equator line, heading north in the sky. This event marks the start of spring in the northern half of the globe. After this date, the Northern Hemisphere begins to be tilted more toward the Sun, resulting in increasing daylight hours and warming temperatures. (In the Southern Hemisphere, it’s the opposite: the March equinox marks the start of autumn, as the Southern Hemisphere begins to be tilted away from the Sun.)