Autumn is a time for pumpkin-flavored drinks, shorter days and the return of chilly weather, although it may take longer than usual for summer warmth to fade, in part due to the building El Niño.
Meteorological fall starts on Tuesday, Sept. 1, while astronomical autumn, which takes place on the equinox, begins at 8:05 p.m. EDT on Tuesday, Sept. 22.
From late-season warmth to flooding, tropical impacts and the first snowflakes of the season, here is AccuWeather’s 2026 U.S. fall forecast:
El Niño to drive the fall pattern
“A very strong El Niño will be a dominant signal through the fall,” AccuWeather Long-Range Expert Paul Pastelok said.
El Niño occurs when ocean temperatures near the equator of the eastern Pacific rise above the historical average for an extended period. The ocean and the atmosphere work together over time and can intensify and steer storm tracks around the globe, including tropical activity across the Atlantic basin.
Forecasters say it could evolve into one of the strongest on record, but there will be other factors at play. One is a separate area of the northern Pacific Ocean that is much warmer than historical averages, which could alter the track of storms, especially over the West Coast. Other factors include the warm waters in the Gulf and widespread drought conditions in the U.S. How these factors interact with El Niño will ultimately dictate the weather throughout autumn.
Where will fall feel the warmest?
September may feel more like an extension of summer across parts of the country, especially in the mid-Atlantic and southeastern U.S., where the above-average temperatures will be paired with high humidity and warm nights.
It may not be until October before the first intrusions of chilly air arrive in the north-central Plains, Great Lakes and Northeast, but these cold outbreaks are not expected to be long-lasting.
Worsening drought could also contribute to the warmth, including in the mid-Atlantic, interior Northwest and across the Rockies, where there are pockets of extreme to exceptional drought. The same dry pattern may also keep wildfire danger elevated into early fall, resulting in episodes of smoky conditions downwind of large blazes.
There may be one upside to the warmer and drier pattern. Later in September and early October, more sunny days and cooler nights could help create bright fall foliage in the Northeast and parts of the Midwest. AccuWeather will release its detailed fall foliage forecast on Aug. 26.
Tropics could still bring US impacts
Two storms have already made landfall along the Gulf Coast this year, Tropical Storm Arthur in June and Tropical Storm Bertha in July, but this may not be indicative of a busy hurricane season.
Get Your AccuWeather Forecast“In the Atlantic basin, El Niño may hold back the number of named storms in 2026, but there can still be several impacts on the United States,” Pastelok said.
The areas facing a higher-than-average risk of direct tropical impacts include the northern and eastern Gulf Coast and the Carolinas. The northeastern Caribbean is also at an increased risk.
September and early October will be the key window to watch for tropical impacts along the mid-Atlantic coast, southern New England and parts of the Carolinas. Tropical storms and hurricanes that track close to the coast could bring flooding rain, high surf and gusty winds.
Read AccuWeather’s full breakdown of the Atlantic hurricane season forecast through the rest of 2026.
Severe weather, flooding risks to shift south
“The severe weather focus should gradually shift from the northern part of the Plains and Midwest toward the southern part of the Plains, Gulf Coast and the Tennessee Valley through the fall,” Pastelok said, adding that this shift is typical during the course of the fall.
The combination of the El Niño-driven weather pattern and warm water from the Gulf will help to fuel thunderstorms and heighten the flood risk, especially during the second half of the season, as the frequency of storms tracking across the southern U.S. will increase.
“Reduced Atlantic tropical activity may result in fewer tropical cyclone-related tornadoes across the Southeast,” AccuWeather Severe Weather Expert Alex Duffus said.
Recent rainfall has reduced the severity of the drought in many parts of the East. As El Niño peaks in late autumn, its influence will grow stronger, and more rainfall is expected in the East, good news for further drought improvement, especially in the mid-Atlantic and Carolinas. It should also help make up for the lack of rain from tropical storms and hurricanes along the Gulf Coast states. Despite two storms having made landfall this summer, neither storm featured widespread rain across the region.
Across the interior Southwest, a strong end to the monsoon season could bring rain to Arizona, Southern California and southern Nevada in September ahead of the impending wet season.
“The threat for severe weather will continue the rest of fall in Southern and Central California with possible atmospheric rivers,” Pastelok added.
When will snow arrive this fall?
The first snowflakes of the season will be confined mainly to the mountains but could reach more populated areas later in November.
Late September and early October could bring snow to the highest elevations of the Rockies in Montana, Idaho and Wyoming. Snow may be slower to arrive in the Cascades of Washington and Oregon due to a warmer start to fall.
Snow chances should increase in the Rockies during November, especially in Colorado, Utah and New Mexico, where a couple of early-season snow events are possible.
In the Northeast and Great Lakes, the weather pattern resembles that of 1994, 1997 and 2023, years when early-season snow blanketed parts of the region in late autumn.
“One storm could meet cold air at the same time to produce some snow in late October into November (near-average start),” Pastelok said. “Otherwise, some snow showers can be expected in the higher ground in November.”
Early episodes of cold Canadian air can also set off lake-effect snow in November downwind of the Great Lakes.