September is expected to bring above-average temperatures across most of the United States, according to the latest outlook from Atmospheric G2 and The Weather Company. The Pacific Northwest is the main exception, with cooler-than-normal conditions forecast for the first month of meteorological fall.
September temperature outlook
- Hottest conditions from the Dakotas to Texas: The strongest above-average temperature signal extends from North Dakota south through the Plains and into Texas.
- Warmth from the Gulf Coast to the Great Lakes: Above-normal temperatures are also expected across the Rockies and the mid-Atlantic.
- Slightly warmer in the Southwest and Northeast: Both regions are forecast to remain warmer than normal, although the departure from average should be more modest than across the Plains.
- Coolest weather in the Pacific Northwest: Below-normal temperatures could offer some relief after a difficult stretch of fire weather, making the region the most likely to experience sweater-weather conditions.
September precipitation outlook
The wettest conditions relative to normal are expected across the Four Corners, where the North American monsoon should remain active during its final weeks before winding down in late September.
Above-normal precipitation is also forecast from the northern Rockies and Great Basin eastward through the Plains and into parts of the Midwest.
The Pacific Northwest coast is expected to remain drier than normal despite the cooler temperatures. That dryness could limit the fire-season relief that a cooler month would otherwise provide.
Drier-than-average conditions are also projected across the East and Southeast, including the Great Lakes, upstate New York, much of the Northeast, Florida and parts of the Gulf Coast.
El Niño developing rapidly
A historically strong El Niño is emerging rapidly, according to Todd Crawford, vice president of meteorology at Atmospheric G2 and chief author of the outlook.
The current event is clearly outpacing all other events at this point in their development, including the 1997 and 2015 El Niños.
