March 21 is the 80th day of the year (81st in leap years) in the Gregorian calendar. There are 285 days remaining until the end of the year.
This date is slightly more likely to fall on a Monday, Wednesday or Saturday (58 in 400 years each) than on Thursday or Friday (57), and slightly less likely to occur on a Tuesday or Sunday (56).
In astrology, the day of the equinox is the first full day of the sign of Aries. It is also the traditional first day of the astrological year. In the 21st century, the equinox usually occurs on March 19 or 20, being on March 21 only in 2003 and 2007. The next year in which the equinox occurs on March 21 is 2102.