The first day of Spring is the equinox. I love the idea that there are four key dates here in the Northern hemisphere: The Spring Equinox, Summer Solstice, Fall Equinox and Winter Solstice. In very short and simply terms, the Equinoxes are the dates when the sun is equal parts day and night and the Solstices are when the days are the longest (Summer), or shortest (Winter).
So this year, the Spring Equinox was on March 20th. The hours of daylight will increase until June 20th which is the summer Solstice. From June 20th - September 22nd, the daylight hours will shorten and on September 22nd, day and night will be equal again. From September 22nd - December 21st, the days will shorten and December 21st marks the Winter Solstice when the days will be the shortest. It happens every year but the dates shift around a little. So this past Saturday was the equinox - the day and night (as measured by sunrise and sunset) were equal in time.
There is still some cold in the forecast and we've had snow as late as May before but the longer days make all the difference. It's officially spring and that means it's only going to get warmer and sunnier and things will start greening up. As it is, we're seeing some migratory birds back (redwinged blackbirds and robins already), crocus are blooming and daffodils are poking up from last year's leaves. We're excited for all of it!