A frigid air mass sweeping across the central United States is set to push eastward by today, delivering a sharp and widespread cooldown.

Temperatures are expected to plunge 10 to 20 degrees below normal, forecasters said, with the chill reaching deep into the South, where overnight lows could dip to freezing.

Brian Hurley, a meteorologist at the Weather Prediction Center, said Sunday that temperatures had started to fall, particularly in northern North Dakota, where readings had dipped to below zero.

“The cold air is going to continue to filter across the central part of the United States today,” he said. “Then tonight, and then on Monday, many areas in the Eastern part of the United States are really going to feel the effects.”

Conditions will also turn wintry and blustery as a storm

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