March 20, 2017 all-day
In the Northern Hemisphere, spring begins today with the vernal equinox, at 6:29 AM, EDT. Note that in the Southern Hemisphere today is the beginning of autumn. Sun rises due east and sets due west everywhere on Earth (except near poles), and the daylight length (interval between sunrise and sunset) is virtually the same everywhere today: 12 hours, 8 minutes.
Image courtesy of wikimedia commons.