First Day of Spring Returns This Thursday – Here's Why

You've undoubtedly heard it before, but spring is almost here. The Sun is poised to take a significant step in its journey northward.

Spring will arrive in the wee hours of Thursday morning this week. If you believe you've heard this before, you're not incorrect.

Our friendliest star will line up with the Earth's equator this time.

The Northern Hemisphere transitions into astronomical spring when the Sun's rays do this. Spring begins on the East Coast at 5:01 a.m. EDT, whereas on the West Coast, it begins at 2:01 a.m.

So, what happened the last time we said spring was coming?

The meteorological spring began on March 1. That seasonal relative of astronomical spring is characterized as a three-month period in which temperatures normally rise. The more rigorous monthly framework makes it easier for 

meteorologists to keep records.

In contrast, astronomical spring shifts in time and date based on when the Sun's rays cross from the Southern Hemisphere to the Northern Hemisphere. This can shift the start of spring from March 19 to March 21.

The balance of day and night occurs when the Sun moves across the equator. During the spring, the amount of daylight will rise.

During an equinox, the Earth's axis of rotation is perpendicular to the line linking the Earth's and Sun's centers rather than tilting away from or toward the Sun.

As a result, over the world, day and night are roughly equal in length. This is demonstrated in the satellite loop below, which alternates between half-sunlit and half-nighttime (dark areas).

From this point forward, daylight in the Northern Hemisphere will progressively increase until the summer solstice on June 20. This is because Earth's Northern Hemisphere will be tilting toward the Sun.

If you're reading this from Down Under, the March equinox signals the start of fall.

As the Earth tilts from the Sun, daylight will become shorter until June, when winter begins in areas such as Australia and South America.

Jonathan Belles has been a graphical meteorologist and writer for weather.com for 8 years. He also contributes to producing videos for The Weather Channel en español. His preferred weather is tropical, although he also enjoys covering high-impact weather, news stories, and winter storms. He has two degrees from Florida State University and is a proud St. Petersburg College graduate.