Long Duration Dryness Ohio Valley to Southeast U.S. Closes Calendar Summer

Climate Impact Company Week 2-4 Outlook

North America

Issued: Tuesday, September 9, 2025

Highlight: Warmth biased Interior East/Southeast, Cooler Interior West. Expanding East U.S. drought.

Chart of the day: Max dry duration forecast for U.S. AG Belt.

Discussion: Late calendar summer dryness is excessive across the East/South U.S. as GFS indicates 360 consecutive hours of no rain from Central Texas to Western Pennsylvania and into the Southeast U.S. Consequently, drought development during late meteorological summer in the Ohio Valley is likely to expand southward.

Week-2 Ahead Forecast valid September 14-21, 2025: Ohio Valley/Southeast U.S. dryness.

Discussion: The outlook shifts wetter/cooler Interior West to western Great Plains. Northern California and the Coastal Northwest are dry and very warm. Southern California and the Desert Southwest are wetter. Anomalous warmth dominates dryness across the eastern half of the U.S.

Week-3 Ahead Forecast valid September 21-28, 2025: Southeast welcomes some rain; Very warm to hot in that region.

Discussion: Low pressure is evolving across the U.S. causing a showery regime to expand from the West to the South U.S. The wet weather in the Gulf States is not related to a tropical cyclone. The Southeast U.S. is very warm to hot and humid while much of the West remains temperate.

Week-4 Ahead Forecast valid September 28-October 5, 2025: Drier again East; Interior West cooler.

Discussion: The East-central and Southeast U.S. reverses drier again as October arrives. The Interior West is cooler, and wet weather affects the Canadian Prairies and New England States. A tropical system is traveling westward in the southern Gulf is possible although west-traveling tropical systems in early October in that location are uncommon.