WASHINGTON – Enjoy the final days before the official arrival of fall because it is going to feel more like summer here in the D.C. area!
Temperatures throughout this last week have been running below normal giving us a little taste of fall. However, this weekend temperatures will top out in the 80s for much of the region thanks to high pressure clearing out cloud cover and helping boost temperatures along with a light southeasterly flow.
A cold front will cross the area Sunday, which will give way to some clouds and about a 30 percent chance of showers in the afternoon and evening hours that will move from west to east. This cold front will also sweep away any of the summer-like weather we have left and leave us with another spell of autumn weather around the region.
The change in temperatures is happening right on time as the autumnal equinox arrives at 10:29 p.m. on Monday. People celebrate this moment across the world when the the sun passes directly over the equator. This happens twice a year as you may recall, in the spring and autumn.
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In Latin, the word “equinox” means “equal night” –“equi” meaning “equal” and “nox” meaning “night.” This signifies the equal parts of daylight and darkness.
However, this is not always the case. The sun will rise at 6:55 a.m. Monday and will set at 7:07 p.m. This isn’t exactly equal. In fact, we have to wait until Tuesday, the first full day of autumn to get the full equal light, equal night. The sunrise on Tuesday will be at 6:56 a.m. and the sunset will be at 7:06 p.m.
My colleague Eileen Whelan summed it up correctly when she wrote:
“We have the atmosphere to thank for this oddity. Also, the definition of sunrise and sunset. Sunrise occurs the moment the tip of the sun can be seen on the horizon and sunset is the last minute the sun can be seen before it dips below the horizon. Also, keep in mind our atmosphere refracts, or bends, light, which makes it appear as if the sun is rising or setting earlier.
The true equinox occurs when the center of the sun’s disk crosses the celestial equator and this occurs at 10:29 p.m. EDT on Monday, Sept. 22. At the same time the equinox occurs in D.C., it occurs across the globe.”
Either way, you won’t notice a difference from Monday to Tuesday, from summer to autumn. However, you will notice that the hours of daylight will grow shorter up until the winter solstice, which begins at 6:03 p.m. EST Dec. 21. This will also be the darkest day of the year – meaning the day with the least amount of daylight.
However, as we make the transition into fall, it may seem a little cooler according to the outlook from the Climate Prediction Center. But, according to the 8- to 14-day outlook, temperatures may be a little on the warmer side!
So don’t swap those flip-flops for boots just yet. Fall is here to stay but bouts of summer may stick around until early October!
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The 6- to 10-day outlook (left) shows a chance for cooler temperatures in the Mid-Atlantic. However the 8- to 14-day outlook (right) shows a chance for warmer than average temperatures nationwide. (Climate Prediction Center and WTOP)
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