CHICAGO, ILLINOIS — A taste of fall is on the way. After the recent stretch of heat, a noticeable pattern change is showing up for next week, according to a mean temperature anomaly map from BAMWeather, based on EPS 5-day ensemble data valid September 21 through September 26, 2026. Cooler air is expected to spread across much of the Midwest, Great Lakes and Northeast, bringing temperatures below normal for a solid stretch of days.
Chicago, Milwaukee and Detroit Run 4 Degrees Below Normal
If you’re in Chicago, expect temperatures to average 4 degrees below normal from September 21 through 26, matching the same anomaly forecast for Milwaukee and Detroit. This trio of Great Lakes cities sits right in the heart of next week’s cooldown, meaning residents across this stretch of the Midwest should plan for a noticeably crisper week than what’s been typical for late September so far.
Cleveland and Pittsburgh See an Even Sharper Cool Down
Just east of the Chicago-Detroit corridor, Cleveland and Pittsburgh are both forecast to run 4 degrees below normal as well, part of a broader band of blue shading on the map representing some of the most consistent cooling anywhere in the country. If you’re in either of these cities, this stretch of days is shaping up to deliver genuine fall-like conditions rather than just a brief dip before warmth returns.
Buffalo and Syracuse Lead the Nation With a 5 Degree Departure
Farther east, Buffalo and Syracuse are forecast to see temperatures run a full 5 degrees below normal, among the largest departures anywhere on the map. If you’re in Upstate New York, this cooldown should feel especially pronounced, with the deep blue shading over this region indicating one of the most confident and significant cooling signals in the entire outlook.
Boston and Burlington Also Face a Sharp 5 Degree Cool Down
Across New England, Boston joins Buffalo and Syracuse with a forecast 5-degree departure below normal, while nearby Burlington, Vermont, comes in just behind at 4 degrees below normal. If you’re anywhere across New England, next week looks like a genuine preview of autumn, with this stretch of days trending meaningfully cooler than what residents have grown used to through the recent heat.
Washington DC and Philadelphia Also See a 5 Degree Drop
Down in the Mid-Atlantic, Washington, D.C., is forecast for a 5-degree departure below normal, matching Philadelphia’s own 5-degree drop. If you’re in either city, this represents one of the more significant cooldowns anywhere along the East Coast, putting D.C. and Philadelphia right alongside Buffalo, Syracuse and Boston as areas seeing the sharpest departure from typical late-September warmth.
New York City and Toronto Round Out the Deepest Cooling Zone
New York City falls within this same deep-blue cooling zone as well, part of a broad stretch running from the Great Lakes through New England and down into the Mid-Atlantic. Just across the border, Toronto and Ottawa are both forecast for 4-degree departures, showing this cooldown extends well beyond U.S. borders into southern Canada as the same pattern change sweeps across the region.
Minneapolis, Des Moines and Omaha See a Milder Departure
Farther west, the cooling signal grows noticeably weaker. Minneapolis and Des Moines are both forecast for a modest 2-degree departure below normal, while Omaha matches that same 2-degree drop. If you’re in this stretch of the Upper Midwest, expect next week to feel cooler than recent conditions, but not nearly as dramatic a shift as what’s forecast farther east across the Great Lakes and Northeast.
St. Louis, Indianapolis and Cincinnati See Only a Slight Cool Down
Across the Ohio Valley, the departure shrinks even further. St. Louis is forecast right at normal, with Indianapolis at just 2 degrees below normal and Cincinnati at a similarly modest 2-degree drop. If you’re in this part of the country, next week’s pattern change will be noticeable but comparatively mild, especially when set against the sharper cooling forecast for cities like Buffalo or Boston.
Southern Cities From Memphis to Raleigh Actually Run Slightly Warmer
Not every part of the outlined region cools down. Memphis is forecast to run 5 degrees above normal, with Nashville and Knoxville both trending 4 degrees above normal. Farther east, Raleigh shows a modest 2-degree cooling, while Norfolk and coastal Virginia stay closer to normal, illustrating just how sharply this pattern change divides the country, with the Deep South largely holding onto its warmth even as the Midwest, Great Lakes and Northeast trend firmly toward fall.
What This Means for Your Week Ahead
Whether you’re in Chicago, Detroit, Buffalo, Boston or Washington, D.C., this outlook points toward a real, multi-day taste of autumn arriving right as the calendar turns toward the season’s official start. If you’re farther south in Memphis, Nashville or Knoxville, don’t expect the same relief just yet, since this particular cooldown is concentrated across the northern half of the country rather than reaching the Mid-South. Either way, it’s a good week to have layers ready if you’re anywhere within the deep blue shading stretching from the Great Lakes through New England.
