The temperature map of the lower 48 is about to flip. According to the FOX Forecast Center, more than 300 million Americans will sit above average on Tuesday, Nov. 10, with only a little over 4 million below it. By Saturday, Nov. 14, the count of people on the cold side is projected to top 160 million, and it could climb higher into Sunday.
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The swing is driven by a lobe of cold Canadian air that begins spreading across the eastern United States late Friday. The same Forecast Center forecast keeps the cooler pattern likely in place through the following weekend, so the Saturday count marks the start of a stretch rather than a one-night dip.
The 300 million to 160 million flip in the forecast
The arithmetic comes from a Sunday-morning forecast published by FOX Weather, in which Forecast Center meteorologists tally how many residents live in places forecast to run above or below the seasonal norm on a given day. Those figures put the early-week split almost entirely on the warm side, a reflection of the long run of unusual warmth that left nearly 50 weather stations with their warmest start to autumn on record, as FOX reported in its Nov. 7 coverage.
The reversal after that is steep. Forecasters framed the move from about 4 million people below average on Tuesday to more than 160 million by Saturday as a change in the whole continental pattern, with the cooler regime expected to hold through the following weekend. The phrase used by the Forecast Center was that temperatures turn noticeably colder beginning Friday.
Canadian air across the Plains and East, and how cold it gets
Beginning late Friday, Nov. 13, the air mass spreads over the Northeast, Great Lakes and Ohio Valley first. Daytime highs there could stay in the 30s or 40s, and overnight lows are forecast to fall into the 20s, a stretch of readings that would feel sharply different after an autumn that ran warm across the central and eastern states. FOX’s forecasters listed Ohio, Kentucky, Indiana and Illinois among the places already flirting with the low 30s on Nov. 8.
Farther south the picture is less certain. FOX said the cold could reach the Gulf Coast and Florida by Sunday, but it framed that as a possibility rather than a firm forecast, which is why the national count is worded with “could” and why Sunday’s total is described only as possibly higher. The West runs opposite: California, the Great Basin and the desert Southwest are expected to be 10 to 20 degrees above average, which explains how the national tally can swing so far without every region cooling.
Some of the early signs are already on the ground. FOX reported on Nov. 7 that more than 19 million Americans were under frost advisories or freeze warnings for the following morning, with the alerts reaching from the middle Ohio Valley into Oklahoma, Arkansas, Tennessee and northern Alabama, and its frost and freeze report expected upper 20s to low 30s in Ohio, Kentucky, Indiana and Illinois.
The Weather Prediction Center’s short-range discussion issued on Nov. 8 kept frost advisories in effect for the Ohio and Tennessee valleys and the Southeast, with Monday-morning lows in the 30s.
Jet stream and polar vortex behind the pattern
A strong ridge over the western United States is acting as a chute, according to the Forecast Center, steering Canadian air south and east. FOX stressed that the pattern does not resemble the usual El Nino winter; the polar jet stream is the main driver, and a polar vortex disruption that arrived unusually early gives the background.
The earlier polar vortex analysis from Nov. 6 is a useful counterweight. The Forecast Center said then that models showed no major cold air outbreaks, and that stratospheric changes take several weeks to reach the surface, so a lasting Arctic pattern would most likely appear in late November or December if it comes at all. FOX did not tie the Saturday cold directly to that disruption, and the polar jet stream remained the stated driver, so the forecast reads as a jet-stream event first and a vortex story second.
Local forecast offices and the southern reach
National Weather Service offices in the affected area were already pointing toward the change, though neither posted a Saturday-specific number. The Nashville-area office said on Nov. 5 that weekend lows below freezing were likely in some spots after a cooler and drier stretch, and on Nov. 7 the Louisville office was listing frost advisory and freeze warning links on its front page, next to a hazard banner for flooding in southern Texas.
The unanswered piece is the southern reach. If the Gulf Coast and Florida do cool on Sunday, Nov. 15, the 160 million figure would grow; if the air stalls near the Tennessee Valley, it would stay near the Saturday count. The Forecast Center’s next national update is where that call will show up, along with any revision to how many people end up on the cold side by Saturday.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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