(WHTM) — Schools have been in session for about a month, football is back to full force on weekends, and the temperature is slowly inching its way down our thermometers. All signs that fall is right around the corner. The first day of fall, or the autumnal equinox, is Wednesday, Sept. 22, and to be even more precise, it’s at 3:20 p.m. eastern standard time.

But how did Sept. 22 become the official day? Why are pumpkins such a big thing this time of year? And why is it being called fall when it’s still quite warm outside?

While the first day of a season may feel like a dart was thrown at a calendar, the actual reasoning for such a day is based on science. Specifically, the positioning of the earth and the sun. This is where the term, equinox comes into play. Equinox is based on the Latin word aequus, which when translated means equal, and nox which means night. So equal nights, but which nights are equal?

Don’t worry, time zones aren’t magically disappearing. When an equinox happens, the sun is crossing the equator from one side to the other. Those of us north of the equator start experiencing fall-like weather during the autumnal equinox while those south of the line start experiencing spring because the sun crosses from the northern hemisphere to the southern hemisphere and vice-versa on the first day of spring. So for the one day when the sun is right on the equator, both hemispheres enjoy roughly the same amount of daylight.

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With the sun’s warmth slowly fading away, when can we expect to start feeling the cooler temperatures and say goodbye to the short sleeves? According to abc27’s Chief Meteorologist and farmer Eric Finkenbinder, “We’ll be dropping in the 50s in the mornings and by the end of the week only hitting 70 for a high. Given the pattern we see developing, I would say the last week of Sept. and into Oct. will offer sweater-type weather.”

With the shift in climate, comes a shift in produce as well so what you see in the “locally grown” section might start to take a different shape. “Pumpkins and apples are your big fall foods. People love spending an afternoon just to go and pick them. Decorating is big too. Pumpkins, corn shocks, gourds, Indian corn. Farmer’s markets will start selling cool-season crops like broccoli, cauliflower, brussel sprouts, and cabbage,” Finkenbinder said.

One last thing to remember, just because we are hitting the first day of fall, doesn’t mean our clocks are “falling back.” That won’t be until the end of daylight savings time on the first Sunday of Nov. which this year is Nov. 7.