When is First Day of Spring in 2015?

The first day of Spring in 2015 is on Friday, March 20th. 

What is First Day of Spring?

The first day of Spring is also known as the Spring Equinox. The word equinox comes from the Latin words "aequus" meaning equal and "nox" meaning equal. So, in essence, the Spring Equinox occurs around mid-March when daytime and nightime are of identical duration - 12 hours daytime, 12 hours nightime. This occurs between the summer soltice (longest daytime of year) and winter soltice (shorest daytime of the year). 

The season of Spring is one of the four typical temperate seasons that occur throughout the calendar year. It falls after winer and is before summer.