There are two different "falls" in the world of meteorology. Meteorological fall begins on Sept. 1, while the autumnal equinox, which people are more familiar with, begins a few weeks later.

There is a scientific reason for the different start times, and maybe I can convince you that meteorological fall is better.

Let's start with the equinox

Fall equinox, astronomical fall or the autumnal equinox. They are all the same.

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The fall equinox is the moment when the sun's most intense rays are directly located over the equator. This means that there is roughly 12 hours of day and 12 hours of night on that day.

(FALL OUTLOOK: Strengthening El Niño is taking charge)

It changes slightly every year, and this year it takes place at 8:05 p.m. EDT on Sept. 22.

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The fall equinox is the second roughly 12-hour day and night in the year after the spring equinox. They come between the solstices, moments of the greatest discrepancy of day and night, depending on where you live.

Meteorological fall

Meteorologists use slightly different criteria, and no, it isn't just that we are as sick of summer heat as you might be. There is science behind this alternative.

Meteorological fall spans from Sept. 1 to Nov. 30. That's because it has to do with a pattern observed from the average temperatures throughout the year.

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The coldest three months of the year in the Northern Hemisphere, opposite for the Southern Hemisphere, are usually from Dec. 1 to the end of February. Meanwhile, the warmest months of the year are from the beginning of June to the end of August.

Meteorological fall serves as the transition from the hottest months of the year to the coldest, as the graph below shows.

These monthly averages don't line up as well with the astronomical seasons; the seasons defined by the equinoxes and solstices.

But you don't have to look up the date when meteorological fall starts. It's Sept. 1 every year.

And it would be silly to wait to say winter is here until a few days before Christmas, so meteorological seasons do help you 'tis the season a little earlier.

Temperatures and daylight fall

We all know the days get shorter and the temperatures drop as fall progresses. But, by how much?

Factoring in daylight saving time, sunsets happen at least two hours earlier by the end of November compared to when they are observed at the beginning of September.

(WATCH: Leaves turning red already? It’s a distress signal)

This increases the farther you move north, nearing a three-hour difference.

With the decrease in sunlight, the average highs follow. The graphic below shows the shift for some major cities, including New York City, Miami, Chicago, Dallas, Los Angeles and Seattle.