AccuWeather 2023 US fall forecast

AccuWeather 2023 US fall forecast

The days are getting shorter and fall is approaching, but when will cooler conditions return, and will snowflakes fall before Halloween? Get the answers to these questions and more with AccuWeather’s annual fall forecast.

AccuWeather’s fall forecast has been released and our remote experts say some parts of the U.S. could see cold and snow early in the season.

Widespread heat has broken records from coast to coast throughout the first half of summer, but the longest days of 2023 are in the rearview mirror and cooler weather is on the horizon.

Astronomical fall officially arrives on Saturday, September 23, at 2:50 a.m. EDT, just a few weeks after atmospheric fall arrives. No matter what date you celebrate the start of fall, it may be a while before fall weather takes hold across the country.

A woman walks past fall foliage during blowing snow, Tuesday, Nov. 12, 2013, at Independence Mall in Philadelphia. (AP Photo/Matt Rourke)

AccuWeather’s team of long-range forecasters, led by veteran meteorologist Paul Pasteluk, analyzed weather patterns around the world to compile a weather forecast for the United States this fall.

One of the driving factors behind weather patterns across the United States this fall will be El Niño, a regular weather pattern that can reshape the jet stream. El Niño developed early this year when water temperatures near the equator in the eastern Pacific Ocean rose to at least 0.9 degrees Fahrenheit above the historical average. This pattern has replaced its cooler counterpart, La Niña, which has persisted for three consecutive years.

Other factors weighed on forecasters’ minds, including sea surface temperatures in the Atlantic Ocean and what happened in previous years when conditions were similar.

So get ready for bonnet weather, pumpkin spice, and vibrant foliage with this region-by-region seasonal forecast:

Meteorological fall begins on September 1, but summer weather will continue into the new season for millions of people throughout the Northeast and Midwest.

Temperatures can reach around 90 degrees in New York City and Philadelphia during the first or second week of September, slightly beyond the historical average for the last day of 90 degrees. In Chicago, the last 90-degree day of the year may not occur until the latter part of September.

The persistent heat could be good news for people planning trips to the beach after Labor Day weekend, but the warm weather will start to break down as the calendar flips from September to October.

The colors of fall foliage at Franklin D. Roosevelt’s Four Freedoms Park, Thursday, November 8, 2018, in New York. The Manhattan skyline lies across the East River. (AP Photo/Mark Lenihan)

Pastelok explained that a “big shift” in the weather will bring in colder air at the end of September in the Midwest and Northeast. Cold air colliding with warmth and moisture will ignite thunderstorms, including the risk of a severe weather event.

The change in pattern could also bring an early frost in parts of the Midwest toward the end of September or early October, including major metro areas like Chicago, Milwaukee, St. Louis and Minneapolis.

The first frost of the season will last into October for the Northeast, and possibly into early November for areas closer to the coast, which is more than a week later than the historical average. This could extend the growing season for farmers and gardeners across the region.

The arrival of cold air across the Midwest and Northeast will also open the door for snowflakes to fall for the first time in months.

“I think we could start to see some fluctuations in the higher elevations as we get into late September and October, but the lower elevations could wait until later in October or November,” Pastelok said. It is not uncommon for these areas to experience snowstorms in October, but they are about two weeks ahead of the historical average for the first snowflakes of the season.

Snowfall will likely be limited to just flurries before the potential for widespread snow accumulation forces people to dig shovels of snow out of storage.

A growing El Niño phenomenon tends to put a damper on tropical activity across the Atlantic Basin, but people in hurricane-prone areas of the United States shouldn’t let their guard down this season.

The biggest factor in hurricane forecasts, other than El Niño, is water temperatures across the Atlantic Basin, which are well above average in many areas. Warm water is the fuel for tropical systems. The warmer the water, the more energy available for storms to utilize.

Sea surface temperatures were particularly noteworthy in the waters of the Gulf of Mexico, where a marine heat wave continues near Florida. Water temperatures off the coast of South Florida and around the Florida Keys soared into the upper 90s to 100 degrees Fahrenheit in July.

Map of the Atlantic Hurricane Basin showing sea surface temperature anomalies. Yellow, orange, red and pink areas appear where water temperatures are above the historical average. Blue and green areas show where water temperatures are below the historical average. (NASA Worldview)

Last year, Hurricane Ian was strengthened by unusually warm waters off the coast of Florida, which helped the system quickly intensify before it made landfall as one of the strongest hurricanes in Florida’s history. Post-storm analysis found that Ian briefly intensified to Category 5 strength while over the Gulf, but made landfall as a Category 4 near Fort Myers, Florida.

“We could see one or two systems going into the warm water pool and exploding,” Pastelok said. “There may be rapid development, and this may be the biggest impact to occur in this tropical season.”

This satellite image taken at 3:06 PM EDT and provided by NOAA shows Hurricane Ian making landfall in southwest Florida near Cayo Costa, Florida, on Wednesday, September 28, 2022, as a catastrophic Category 4 storm. (NOAA via AP)

The most active period in the tropics can be late August and September, near the traditional peak of the Atlantic hurricane season. If El Niño intensifies throughout the fall, it may limit tropical growth in October and November.

Thunderstorms can also regularly flood the Southeast among tropical threats. At times, stormy weather may reach areas further north as well.

“The transition period in late September and October could be very active for parts of the southern Midwest and western Ohio Valley extending into the mid-Mississippi and lower Mississippi Valley,” Pastelok said.

Summer weather will hover over the Southeast during the first part of fall before eventually giving way to cooler, less humid conditions late in the season, Pastelok added.

The central United States and the Rocky Mountains are experiencing a major shakeup after a mild start to the fall.

When formulating weather forecasts for an entire season, meteorologists look to the past to help predict the future. “We look at other years and try to match the current pattern or what we expect to happen over the next couple of months,” Pastelok explained. These are known as analog years.

One notable analog year is 2009. That year saw a major snow storm on October 8, which unloaded a foot of snow in Nebraska.

“There’s a good chance we’ll see something similar (this year),” Pastelok said. “The pattern change that occurs could bring more cold into the northern central Plains states and back into the northern Rockies.”

Even if snow is not widespread in the central United States during October, temperatures across the region are expected to be lower than last October, including Denver, Dallas and Kansas City.

Even if these areas get snow in October, the chance of snow will likely decrease somewhat in November. Temperatures across the Rockies and Plains may also rebound slightly in November with widespread temperatures slightly above the historical average.

It’s been a hot summer across much of the western United States, and that trend will continue into the early fall.

“Summer will probably last a little longer, especially in the Southwest,” Pastelok said. “California, central valleys, and deserts will likely remain hot at least through October.”

However, a much different story will unfold across the Pacific Northwest. “There’s a possibility that some wet weather could come in pretty quickly in September, and maybe even the possibility of an atmospheric river,” Pastelok said.

A pedestrian huddles under an umbrella near a tourist shop during steady rain on Monday, November 26, 2018, in Seattle. (AP Photo/Eileen Thompson)

While the wet pattern won’t continue across the Pacific Northwest throughout the fall, an early rainstorm or two could help limit the wildfire season across the region.

The U.S. wildfire season has gotten off to a slow start, thanks in part to a heavy winter season that saw several moisture-laden storms batter the West with historic amounts of snow and heavy rain. However, this slow start to the fire season may not last.

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“Even though we are off to a late start, and the season may be shorter this year compared to other years, we may see the space growing quickly,” Pastelok explained.

The highest fire risks this year are expected to be in northern California, eastern Oregon, eastern Washington, Idaho and parts of Nevada.

Additionally, there may be more Santa Ana wind events in October than last year, helping to fan the flames of fires across Southern California.

Some fires may break out in October, as winds fan the flames, causing fires to increase in California, Pastelok said.

AccuWeather meteorologists say wildfires will likely burn between 5 and 6.5 million acres across the U.S. this year, less than the historical average of 7 million and less than last year’s total area burned of 7.5 million. acres across the country.

Are you looking forward to seeing colorful foliage this fall? Check back on Friday, September 1, for AccuWeather’s U.S. fall foliage forecast.

Fog sits in the Valley of the White Mountains as tree leaves change colors, Sunday, Sept. 28, 2014, in this photo taken from Milan Hill in Milan, New Hampshire. (AP Photo/Jim Cole)

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