Farewell flip-flops, hello pumpkin spice: The autumnal equinox is Wednesday

• Our long, hot summer is finally coming to an end on Wednesday.
• The exact time of the equinox is 3:20 p.m. EDT.
• Although astronomers say summer ends Wednesday, meteorologists say summer ended Aug. 31.

Farewell, flip-flops. And hello pumpkin spice.

Our long, hot summer is finally coming to an end on Wednesday with the autumnal equinox, which marks the beginning of fall here in the Northern Hemisphere.

At a precise moment each September, usually on the 22nd or 23rd, the sun is directly above the equator, marking the autumnal equinox in the Northern Hemisphere.

South of the equator in the Southern Hemisphere, it's known as the vernal or spring equinox and marks the beginning of spring. 

What time is the autumnal equinox?

The exact time of the equinox is 3:20 p.m. EDT. The equinox occurs at the same moment worldwide, according to the Old Farmer's Almanac.

The word equinox comes from the Latin words "aequalis" and "nox," meaning equal night. On the autumnal (and the spring) equinox, day and night are both roughly 12 hours long in most of the world.

This will be true Wednesday from as far north as Utqiagvik (formerly Barrow), Alaska – north of the Arctic Circle – to as far south as Wellington, New Zealand, the world's southernmost capital city.

Day and night aren't exactly 12 hours long on the day of the equinox because the Earth's atmosphere refracts, or bends, light in an optical illusion that brings more daylight than there really is. Because of this, the date when day and night are of equal length is usually a few days after the autumnal equinox.

Another equinox fun fact: On Saturday, the sun rises almost due east and sets nearly due west for most of the world, except at the North and South Poles.

When does fall start?

Although some people say the autumnal equinox is the "official" start of fall, there is no administrative or political organization that actually designates that.

Indeed, though astronomers say summer ends Wednesday, meteorologists and climatologists say summer ended Aug. 31, the final day of the three hottest months of the year (June, July and August).

A summer sizzler:This summer tied the 1936 Dust Bowl for USA's hottest on record

According to the National Oceanic and Atmospheric Administration, the summer of 2021 (June through August) tied with 1936 as the warmest on record for the United States. 

Looking ahead, although some cooler air is on the way over the next few days in the central and eastern U.S., summer may not be giving up all that easily. A NOAA forecast released last week shows milder-than-average temperatures are likely across much of the nation for the next three months.

When do we turn the clocks back?

While the first day of fall is Wednesday, we won't turn the clocks back until Nov. 1, when daylight saving time ends. The clocks are turned back at 2 a.m. by one hour on that day. That means sunrise and sunset will be one hour earlier – and you'll get an extra hour of sleep.