Spring Equinox 2025 Uk. 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 are almost the same. Spring starts on march 20 or 21 and lasts until june 20 or 21.

This equinox is used to measure the length of a tropical year, or how long the earth. The sun entries into the 4 cardinal signs (aries, cancer, libra, capricorn) mark the equinoxes and solstices: