Happy Monday and welcome to another edition of Beyond The Forecast!
Picture it: the last day of summer. A soft breeze dances through the green leaves on the trees. The sun is shining in a bright blue sky with only a few clouds puffing up. The smell of burgers and hotdogs on the grill fills the backyard and you can tell that this meal will end up just a little too crispy.
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But what day is it? And is it always this sunny? Should there be a chill in the air by the time autumn begins? Well, that all depends on what you consider the end of summer.
First things first: the official end of summer is the autumnal equinox in late September (this year that’s Thursday, Sept. 22). The equinox marks the point where we have more hours of night than daylight. The tilt of the Earth stays consistent as it orbits the sun. That means that for half the year the northern hemisphere is tilted slightly more toward the sun, and in the other half, the southern hemisphere gets more exposure.
For a lot of people, the unofficial end of summer is Labor Day, others might think the start of September and for plenty of kids whenever school starts is the end of summer no matter how hot it is outside.
Let’s look at what it’s usually like on Labor Day. Each year the exact date of the holiday changes since it takes place on the first Monday in September, but average conditions are fairly similar across that short amount of time. High temperatures for that first week of the month are in the low-80s on an average day.
While there is a better chance for at least some rain during the dog days of summer the start of September has higher record rainfalls.
If you consider Labor Day the end of your summer, you’ll notice a change from more days with sunshine and afternoon storms to cloudy days with consistent rain.
Labor Day can coincide with the start of Meteorological Autumn, which starts on the first of September. Using that date makes it easier to compare statistics across years without having to account for the shifting dates of the equinox
The first day of school for students in Pulaski and Roanoke Counties was a whole four weeks before Labor Day this year. Going back to school in the middle of August means summer ends for those kids about a month and a half before the equinox.
Temperatures at that point are in the mid-80s on average, and about a third of days in the middle of August have rainfall. That rain is more likely to be brief than at the beginning of September: the rainiest mid-August days see about 5 inches of rain while days at the beginning of September can see as much as 6 inches.
Peak humidity lands in July, but it isn’t much better in the middle of the next month. If mid-August is when summer ends for you, odds are good that it’s still hot and humid for a few weeks into the next season with afternoon storms.
At the autumnal equinox itself in late September, conditions are much more consistently what most of us call fall-like. Average highs are comfortable in the mid-70s, with some consistently rainy days. Humidity is much lower than an average day at the start of the month let alone when compared to the middle of August.
Average wind speeds start an upward trend around the equinox. That coincides with the image of leaves blowing off the trees as they change color.
Days are shorter in September than in August, but the difference is not as drastic as it is from the summer solstice to the middle of August making for one condition that’s rather consistent across all three time periods.
No matter what you consider the end of your summer, the leaves will change, the day will grow shorter and cooler temperatures will work themselves in. Try to enjoy the nice, sunny days ahead no matter which day you prefer. One day or another autumn is still on the way!
There are some more storms to kick off the work week, but we get a few more mild days after the halfway point. You can download our weather app for information on storms as they develop and get Meteorologist Chris Michaels’ latest updates online.
You can always get specific forecast details for your zone, whether it’s the Roanoke Valley, Lynchburg area, the New River Valley or elsewhere around Southwest and Central Virginia, anytime at WSLS.com/weather. Know your zone!
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-- Marshall Downing