When is Spring?

In the United Kingdom, and the rest of earth's northern hemisphere, the first day of spring is on 20 March. On the first day of spring the number of hours of daylight and night are the same, so there are 12 hours of daylight and 12 hours of darkness.

This is because the sun shines directly over the equator, which is an imaginary line that divides the earth, half way in between the North Pole and South Pole.