Fall 2017 Temperature Outlook: Warmer Than Average For Much of U.S., Except Cool in Northwest

Linda Lam
Published: July 16,2017
A warmer-than-average fall may be in store for areas from the Southwest into portions of the Midwest, according to the latest outlook from The Weather Company, an IBM Business.
Much of the East, South, as well as the northern Plains into parts of the Rockies, will likely see temperatures near or slightly above average during the September through November time period.
(MAPS: Weekly Planner and 30- and 90-Day Outlooks)
Near-to-slightly-cooler-than-average temperatures are most likely in the Pacific Northwest.

Fall 2017 temperature outlook from The Weather Company, an IBM Business.

The development of El Niño is currently not likely to occur this fall and winter, which is one of the factors considered in the temperature forecast over the next few months.
"It appears as though the weak attempt at El Niño has failed, and latest models and observations suggest that the La Niña base state is here to stay," said Dr. Todd Crawford, chief meteorologist with The Weather Company.
The most recent outlook from NOAA said that ENSO-neutral conditions are favored, a 50-55 percent chance, into the Northern Hemisphere winter. El Niño is the warming of the equatorial eastern and central Pacific Ocean temperatures, while La Niña is the cooling of water temperatures in that region.
This change from possible El Niño conditions developing does impact the fall forecast, as El Niño and La Niña can have impacts on weather patterns across the globe.
(MAPS: Average Monthly Temperatures)
Another factor that was considered with this forecast is the expectation of the development of a negative North Atlantic Oscillation (NAO) at times. Crawford notes that if a negative NAO pattern does not return it could mean warmer temperatures than currently anticipated for the Northeast and north-central U.S.

September

The overall pattern that has been present for much of this summer is expected to generally continue into September.
(MORE: Mid-Summer Report Card)
A swath from the Southwest into the Upper Midwest will likely see warmer-than-average temperatures in September, while areas from the southern Plains into the Northeast are expected to experience temperatures near to slightly-above average.
Areas of the Southeast, as well as in portions of Oregon and western Washington, are more likely to see temperatures near to slightly below average.
Crawford notes that disruptions in the upper-level pattern are possible from recurving tropical cyclones in both the North Pacific and North Atlantic oceans.

September 2017 temperature outlook from The Weather Company, an IBM Business.

October

The only area of the continental U.S. that is expected to see near-to-slightly-cooler-than-average temperatures in October is the Pacific Northwest.
However, a widespread area of above-average temperatures is expected from the eastern Great Lakes into the Midwest, central Plains and Southwest.
Much of the South and Northeast will likely see near-to-slightly-above-average temperatures.

October 2017 temperature outlook from The Weather Company, an IBM Business.

November

The area of warmer-than-average temperatures will shift into the souther tier of the U.S. in November.
Meanwhile, the Northeast into the Midwest, Great Basin and central and northern California can generally expect near-to-slightly-warmer-than-average conditions.
Near-to-cooler-than-average conditions will likely expand from the Pacific Northwest into portions of the northern Plains, as we head closer to winter.

November 2017 temperature outlook from The Weather Company, an IBM Business.

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The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.