Don't believe your calendar! This is not the "first day of spring."
Alright, I'm just making a soapbox speech here --- but it bugs me that people call this day what it isn't.
Today is the Vernal Equinox, or the Spring Equinox: the sun is at a particular midpoint in its ecliptic in relation to the equator, and the sunrise and sunset are exactly twelve hours apart. "Equinox" literally means "equal night" in Latin.
Spring is a climatic season that varies every year and at every location; it's not a specific calendar time!
I have no idea who thought he or she had the authority to pronounce that today is the first day of spring, and I don't know why calendar publishers do what they do, but let's face the facts and question that unidentified "authority"!
Let's rightly call it the Spring Equinox!