The calendar may say April, but the atmosphere is saying February across much of Europe and northern Africa. A potent cold blast, accompanied in some spots by a rare late-season snowfall, will surge south to kick off the workweek, bringing a sudden seasonal reversal to some places that just observed their warmest March weather recorded. Last week, the Netherlands, France, Belgium and Luxembourg established record temperatures for the month of March, while stations across broader Europe and even into Asia smashed record readings for the date. In Paris, the mercury soared to 78 degrees on March 31, its highest temperature on record for the month, according to AccuWeather.

High temperatures some 20 degrees or more above average will be replaced by a sudden chill, courtesy of an active jet stream pattern that favors hefty shifts.

Some computer models even indicate the potential for a dash of snow in Venice and along the shores of the Mediterranean, with snow also favored in Turkey and over the Black Sea. Snow was already falling in Germany on Monday.

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The leading edge of the cold air was crashing south across the northern tier of Europe on Monday, having already plowed through the United Kingdom with overcast skies and a thick, dense low cloud cover. By midnight, most of Europe will be on the chilly side of the boundary, which will collapse into the Mediterranean on Tuesday and pivot east on Wednesday.