Late Summer Heat Will Continue This Week Across the South and East

Tom Moore
Published: September 18,2016
It's been a long, hot summer across the eastern U.S. and significant relief is not arriving this week.
For many cities across the eastern U.S., this was one of the hottest meteorological summers (June-July-August) on record. This trend has continued through the first half of September and it doesn't appear that there will be any changes through next week.
Temperatures will be on the increase into early this week for the eastern two-thirds of the country. Daily highs will range from 5-15 degrees above average through late week, from portions of the Midwest to the South and Northeast.

Forecast Highs

Timeline

Monday: The heat will start kicking into high gear across most of the U.S. including portions of the Southwest, South, East, and Midwest. Temperatures are expected to be 5-15 degrees above average.
(MORE: Summer 2016 Was One of the Hottest on Record in the Lower 48 States, Says NOAA)
Tuesday: The heat will shift out of the southwest due to added moisture from Paine, but the central and eastern portion of the country will stay warmer than average. Portions of the Northeast and Northern Plains could see temperatures 10-18 degrees above average.
Late Week: The forecast through late week is for unseasonable warmth to continue across the eastern half of the country. Many cities will see high temperatures from 5 to 15 degrees above average at times. A cold front will slowly eliminate warmth in the northern tier of the U.S. from northwest to southeast.

Next Week's Forecast For Eastern Cities

How Warm Have We Been?

Here are some examples of eastern cities indicating their average temperature this September (through Sept. 16) and number of degrees above average.
Some locations are running 4 degrees or more above average for September and there is nothing to indicate that these values will be dropping anytime soon.

City	Average Temperature (F)	Degrees (F) Above Average
Hartford	70.8	4.1
New York	74.7	4.2
Washington, D.C.	77.6	5.5
Raleigh	77.6	3.3
Atlanta	79.9	4.1

(MORE: La Niña Likely to Be a No Show This Fall and Winter)

Setup For Prolonged Heat

A persistent high pressure ridge (bulge in the jet stream) has kept temperatures well above average across the eastern U.S.

For the past few months, there has been a persistent high pressure ridge (bulge in the jet stream) across much of the eastern U.S.
During these periods the air sinks and warms, allowing temperatures to climb.
Humidity levels have also been quite high and the increased moisture traps the heat of the day.
As a result, much of the heat isn't allowed to escape into the atmosphere and that allows overnight temperatures to remain elevated.
This general pattern is likely to persist for awhile.
There are some computer models that indicate cooler conditions are possible across the East toward the end of the month.
MORE: Warm Weather Fun