Torrential rain, heavy thunderstorms and howling winds are forecast on Halloween all the way from Texas to the Midwest and interior sections of the Northeast, according to AccuWeather meteorologist Andy Mussoline.
Almost 42 million people could contend with severe thunderstorms Thursday, the Storm Prediction Center warns, with cities such as Cincinnati, Indianapolis, Louisville, Memphis, Nashville and Houston all at risk.
"Damaging winds and some tornadoes will be possible with what should be a complex and potentially messy storm," according to an online forecast from the prediction center.
"The best costume in Houston for Halloween probably involves a garbage bag to keep dry," reports WeatherBell meteorologist Ryan Maue, who adds that it could be the wettest Halloween ever in some spots.
Because of the threat of bad weather, some towns in Ohio, Kentucky and Indiana have moved Halloween events to Friday. Seven Indiana communities are moving trick-or-treating to Friday outright, WTHR-TV reports.
In northwest Ohio, the threat of severe weather has already prompted at least six communities to switch their trick-or-treat plans to the weekend.
Chicago, Detroit, Pittsburgh and Burlington, Vt., will also see rain on Thursday, though no severe storms are forecast.
The worst of the wind will target areas around Lakes Erie and Ontario, where gusts to 60 mph are possible Thursday night into Friday, AccuWeather reports.
Most of the East Coast (from the Mid-Atlantic south) will see a calm and quiet Halloween. Rain should hold off until late evening or the middle of the night in the big cities of the Northeast from Boston to Washington, D.C.
The East will be unusually mild, with highs near 70 degrees as far north as New Jersey.
The majority of the West will also be dry, though a few showers could dampen spirits in coastal areas of the Pacific Northwest, including in Seattle and Portland.
The north-central U.S. will be chilly — with temperatures forecast in the 30s and 40s — but clear for trick-or-treating.
While some light snow is possible in the highest elevations of the northern Rockies Thursday, it will be nothing like Halloween of 1993, when snow fell as far south as Atlanta and temperatures bottomed out in the upper 20s in Corpus Christi, Texas.
Another infamous snowstorm also hit on Halloween, this one in 1846, when a fierce blizzard dumped as much as five feet of snow in the Sierra Nevada in California. The storm, coupled with several others, stranded more than 80 pioneers in the snow, and eventually forced the starving survivors — the hapless Donner Party — to resort to cannibalism to endure the winter.
Contributing: Doug Stanglin, USA TODAY