A brief surge of milder air through Monday morning will be followed by a dangerous cold blast in Philadelphia.
Philadelphia will escape the worst of the snowstorm that is taking aim at Chicago, St. Louis and Detroit.
The track of the snowstorm will instead lead to a brief rebound in temperatures and some rain for Philadelphia through Monday morning.
Also accompanying the rain will be areas of potentially dense fog that will lead to slow travel for motorists and possible flight delays.
Temperatures will return to the 40s from late Sunday through Monday morning.
However, the warming wasn't quite fast enough to prevent a bit of rain from freezing on some surfaces earlier on Sunday. There were many reports of accidents throughout the Delaware Valley, including some speed restrictions on bridges. Along with that, Philadelphia International Airport had a ground stop in effect for several hours.
Slick spots will once again be a concern for motorists and residents as the snowstorm's cold front sweeps through and ushers in dramatically colder air.
Temperatures will plunge from the upper 40s Monday morning to the lower 30s late Monday afternoon, causing any standing water on untreated roads and sidewalks to turn icy. The invading cold air will also cause the rain Monday morning to end as a little snow.
Lows in the single digits Monday night, highs in the teens on Tuesday and dangerously colder AccuWeather.com RealFeel® temperatures will force those in Philadelphia to bundle up to avoid enduring frostbite or hypothermia.
Watch a video from inside of a tornado that touched down near Bashkortostan, Russia, on August 29.
Showers and thunderstorms will return to the Southwest late this week and could reach part of California.
A cold front swinging into the Northeast will bring the threat of severe weather to part of the region on Tuesday afternoon.
Flooding is a concern across southwest Mexico through midweek as Norbert moves just offshore.
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126 degrees - highest ever for U.S. in Sept.
East Coast (1775)
Matecumbe Key, FL (1935)
Labor Day Hurricane hit Florida. Pressure at Matecumbe Key dipped to 26.35"/892.3 mb. Most intense hurricane ever to hit the U.S. with 200-mph wind. Tide of 15 feet; 408 dead.