The first day of spring arrives on Monday, March 20th at approximately 3:28am, PDT as the sun passes over the equator on it's trip into the northern hemisphere.

Balance of Light and Dark

In the third week of March each year, the Vernal Equinox occurs, when the sun is over the equator at high noon and for a brief time is shining "equally" in both the Northern and Southern hemispheres.

Here in Lake Tahoe this year, the Vernal Equinox is the astrological first day of spring and this year, as you may have noticed, spring weather has been clearly evident.

North Pole
The sun will travel northward, relatively, until the third week in June, when the Northern Hemisphere has its longest day, i.e., period of daylight, known as the Summer Solstice. The sun then heads southward again and crosses the equator on the day of the Autumnal Equinox in September.

For more about the Vernal Equinox, visit www.timeanddate.com.

Above is a diagram of the Earth's seasons as seen from the north. Far right: December solstice. Source: Wikipedia