The science behind drastic cool-downs in the fall

Related to daylight changes in northern latitudes

ROANOKE, Va. – It's pretty common knowledge that we see drastic temperatures changes during the fall. That's something we'll definitely notice heading into Thursday afternoon, as we trade the shorts and t-shirts from Wednesday for something a little more cozy.

These drastic temperature changes have to do with the daylight lost, not just here, but in higher latitudes (farther north).

Wednesday, September 26th, marks the day when we have exactly 12 hours of daylight and 12 hours of darkness in Roanoke. While we lose daylight at an average of 1 minute, 42 seconds per day in the fall, other places lose daylight at a quicker pace.


Anchorage, Alaska loses daylight at an average rate of 4 minutes, 36 seconds a day in the fall.


Bismarck and Chicago lose daylight at about 2 to 2 and a half minutes per day in the fall.


The rate at which daylight is lost per day is very similar for a place like Boston, Massachusetts.


This means that these places have a better opportunity to cool down at night. Once cold fronts pass through our area, that cooler air is forced down and results in drastic temperature changes. 

This will happen Thursday, as cooler air from New England is wedged up against the Appalachian Mountains. This means that our daytime temperatures will likely cool into the upper 50s and low 60s.


That's a huge difference from Wednesday's low-to-mid 80s!

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