The first day of spring is a day earlier than typical years. Here's why.

Spring is starting a little earlier than usual this year. 

March 19 at 11:06 p.m. ET will mark the vernal equinox for the northern hemisphere, when the sun's energy is in balance between the northern and southern hemispheres, according to National Weather Service.

The season typically changes on Mar. 20th or 21st. So, why is it spring starting a few hours earlier in 2024?