The March equinox for 2015 occurs at 22.45 UTC (10.45 p.m.) on March 20. This is astronomically when the Sun crosses the celestial equator. You can convert that to your local time using the
world clock converter. UTC is the same as Greenwich Mean Time (GMC), so for people living a few time zones and beyond to the east of Greenwich, the March equinox occurs on March 21 this year.