The vernal equinox happens at exactly 4:58 p.m. today. This moment is not the beginning of spring weather, as that is something that varies with the changeable weather all over the Northern Hemisphere. It is, however, the exact beginning of astronomical spring. This is the part of the year in which the length of daylight exceeds the length of darkness and the amount of daylight increases each day. Upon the summer solstice, which will be June 21, this year, the days remain longer than the nights but each daylight period will be shorter than the previous day.
There is an age-old myth that an egg can be balanced on its end only on the date of the vernal equinox. This is nonsense. Gravity and balance are not uniquely affected on this day. It probably depends on the egg, but most eggs can be balanced on their end on any day and this task will be equally difficult and equally a waste of time on any day.