Winter vacation in Delhi's private schools have been extended till January 15 in the wake of a cold wave in the national capital, a circular from the Delhi government's Directorate of Education said.

Private schools were slated to reopen after winter break on January 9.

"In continuation to the DOE's (Directorate of Education) earlier circular, all private schools of Delhi are advised to remain close till January 15, 2023, in the wake of cold wave prevailing in Delhi," the circular read. A severe cold wave walloped Delhi on Sunday, with the minimum temperature at the Safdarjung Observatory, the city's primary weather station, plunging to a bone-chilling 1.9 degrees Celsius, the lowest in January in two years.

A blinding layer of dense fog enveloped northwest India and the adjoining central and eastern parts of the country, affecting road, rail and air traffic movement. On Saturday, the Safdarjung observatory had logged a minimum temperature of 2.2 degrees Celsius -- lower than that of most places in Himachal Pradesh and Uttarakhand and some hill stations in Jammu and Kashmir.

A severe cold wave is when the minimum temperature dips to 2 degrees Celsius or the departure from the normal limits is by more than 6.4 notches. A cold day is when the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 notches below normal. A severe cold day is when the maximum temperature is at least 6.5 notches below normal.

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