CHARLESTON, W.Va. — Fall officially arrived in West Virginia Tuesday night, but depending on where you live and how you define the season, autumn may have started weeks ago or may still seem a long way off.
The autumnal equinox occurred at 8:05 p.m. EDT Tuesday, marking the astronomical beginning of fall in the Northern Hemisphere.
Meteorologists, however, have considered it fall since Sept. 1. And in West Virginia’s mountains, where elevation can dramatically influence temperature and the timing of fall color, neither date necessarily describes what is happening outdoors.
In fact, on the day astronomical fall arrived, parts of West Virginia still felt distinctly like summer. At Beckley, the National Weather Service recorded a high of 75 degrees Tuesday and a low of 64. The day’s average temperature was 70 degrees, seven degrees above normal.
So when does fall really begin in West Virginia? The answer depends on which fall you’re talking about.
Why are there two first days of fall?
Meteorologists divide the year into four three-month seasons based largely on the annual temperature cycle. Meteorological fall therefore always begins Sept. 1 and includes September, October, and November.
The astronomical seasons are based instead on Earth’s position relative to the sun.
The September equinox occurs when the sun crosses the celestial equator from north to south. This year’s crossing occurred at 8:05 p.m. EDT Sept. 22, beginning astronomical fall in West Virginia and throughout the Northern Hemisphere.
Fixed three-month seasons make it easier for meteorologists and climatologists to compare weather records year to year. The astronomical calendar, meanwhile, follows Earth’s annual journey around the sun.
But West Virginia offers another way to watch the season change.
In West Virginia, fall moves through the mountains
Autumn does not arrive everywhere in West Virginia at once. The state’s landscape rises from relatively low river valleys to mountains more than 4,000 feet above sea level, creating significant differences in temperature, vegetation, and the timing of seasonal change over relatively short distances.
The contrast is especially pronounced in the Allegheny Mountains. The Monongahela National Forest ranges from about 1,000 feet above sea level to 4,863 feet at Spruce Knob, the highest point in West Virginia.
That vertical landscape helps stretch autumn across weeks. Higher elevations generally begin changing color first, with the progression moving toward lower elevations as the season advances. A traveler can therefore encounter forests at noticeably different stages of autumn during a drive of only a few hours.
David W. McGill, a West Virginia University Extension professor and forest resources specialist, told WVExplorer.com that elevation is among the factors influencing the development of fall color, along with temperature, moisture, tree species, slope and other local conditions.
That also makes the precise timing and brilliance of West Virginia’s fall foliage difficult to predict.
A high mountain landscape may already be showing the first unmistakable signs of autumn while forests in warmer valleys remain overwhelmingly green. Weeks later, the high country may be past peak while lower elevations are reaching their brightest color.
In West Virginia, fall is as much a progression across the landscape as a date on a calendar.
The equinox doesn’t mean day and night are exactly equal
Despite the name, the equinox also does not necessarily produce exactly 12 hours of daylight and 12 hours of darkness.
The equinox is an instant—the moment the sun crosses the celestial equator—rather than an entire day.
Earth’s atmosphere also bends sunlight near the horizon, allowing the sun to remain visible slightly before its geometric sunrise and after its geometric sunset. That makes daylight around the equinox slightly longer than 12 hours in many locations.
The nearly equal division between daylight and darkness occurs around the equinox, rather than precisely at the moment it happens.
So when does fall really begin?
There are at least three reasonable answers. For meteorologists, fall began Sept. 1. For astronomers, it began at 8:05 p.m. Tuesday.
For someone watching the mountains of West Virginia, fall arrives gradually as cooler weather and changing forests move through the state’s elevations. That distinction is particularly visible this year.
Only a day before the equinox, Beckley reached 83 degrees, 10 degrees above the normal daily high. The average temperature was 12 degrees above normal, according to the National Weather Service.
Yet elsewhere in the state, the first stages of the annual color progression are beginning in the higher mountains. The calendar now says autumn throughout West Virginia. The landscape will take a little longer to catch up.