When is first day of fall? SC's weather forecast by Old Farmer's Almanac; is it accurate?

If you’re ready for a break in South Carolina’s sweltering summer heat, you might be craving cozier fall weather.

The Old Farmer’s Almanac, a predictive report for farmers dating back to the 1700s, is already counting down to autumn. According to the Old Farmer’s Almanac, autumn is only 53 days away, beginning Sept. 22.

How does Old Farmer's Almanac make predictions?

The Old Farmer’s Almanac is a controversial approach to weather prediction. As previously reported by Erin Walker of Columbia’s WLTX, a five-year University of Illinois study tested its accuracy. The study showed that the Old Farmer’s Almanac was only accurate about 52% of the time, despite the group’s claims that it is accurate 80% of the time.

The Old Farmer’s Almanac marks the beginning of autumn based off the autumnal equinox. While the almanac may not be the most accurate predictor of weather, the United States Naval Observatory, Astronomical Applications Department also expects this year’s autumnal equinox to occur on or around Sept. 22.

What is an autumnal equinox?

The autumnal equinox marks the beginning of astronomical fall. Astronomical seasons are defined by two solstices and two equinoxes, dictated by the way the earth is tilting on its axis.

Solstices occur in June and December, marking the two days the Earth’s Equator is tilted either the farthest toward or away from the sun. In the Northern Hemisphere, June’s summer solstice marks the longest day of the year, while December’s winter solstice is the shortest.

Equinoxes occur when Earth’s axis isn’t tilted toward or away from the sun. During an equinox, there is a “nearly” equal amount of daylight and darkness. The word equinox comes from the Latin words aequus, meaning equal, and nox, meaning night.

While scientific sources tend to predict temperature and precipitation in shorter timeframes, the U.S. Astronomical Applications Department predicts the earth’s equinoxes and solstices, along with other movements of the sun, through 2100.

When will it get cooler in South Carolina?

An equinox doesn’t automatically mean the weather will shift.

While weather in temperate climates traditionally change with the seasons, the equinox defines the earth’s tilt rather than whether it’s cooler or hotter.

In 2023, Earth experienced warmest year on record

Changing climates also play a significant role in the weather. In 2023, Earth experienced its warmest year on record. Each of the 10 warmest years in modern history has occurred within the last decade, something scientists largely attribute to climate change caused by human activity and greenhouse gases.

What will fall be like in Upstate?

According to the Old Farmer’s Almanac, Greenville and Upstate residents should expect to see below-average temperatures in September. However, the National Oceanic and Atmospheric Alliance Center for Weather and Climate Prediction predicts temperatures are likely to remain higher than average in the Upstate through October.

How much rain will South Carolina get this fall?

Experts also expect a La Niña to form this fall, traditionally leaving the Upstate with a drier, warmer winter than other years.

However, the Old Farmer’s Almanac and the Climate Prediction Center expect above-average precipitation in the Upstate from August to October.

Old Farmer's Almanac uses 'secret formula'

The Old Farmer’s Almanac uses a “secret formula” based around sunspots, initially used by the almanac’s founder Robert B. Thomas. As society has progressed, the group includes meteorology and climatology in their predictors, according to their website.

All things considered, maybe wait before breaking your blankets out of storage. But if you want to celebrate the equinox, expect it in just under two months.

Sarah Swetlik covers climate change and environmental issues in South Carolina's Upstate for The Greenville News. Reach her at sswetlik@gannett.com or on X at @sarahgswetlik.

This article originally appeared on Greenville News: Fact-checking Old Farmer's Almanac: When will Upstate feel like fall