Calcutta, Dec. 4 :    Calcutta, Dec. 4:  Calcuttans, brace yourselves for the chill. Sunday's sudden four-degree drop in minimum temperature, from 17.5 degrees Celsius to 13.6 degrees Celsius - the sharpest fall over a 24-hour period recorded in the last 10 years -- had people scurrying for their woollens. The weather office said on Monday that after a brief lull over the next couple of days, the temperatures are expected to drop sharply again. Even though the minimum temperature rose by 0.7 degree to 14.3 on Monday, officials said that about a week from now, winter will intensify again when the high-pressure belt over Rajasthan and Madhya Pradesh, which weakened on Monday, becomes stronger and pushes the North Wind more vigorously towards Calcutta. 'For the next six days, the minimum temperature will hover around 14 degrees Celsius. Then, this high pressure will strengthen and lead to an increase in the North Wind's speed in Calcutta and elsewhere in Gangetic West Bengal. The wind sweeps across Kashmir, Uttar Pradesh and Bihar before reaching Calcutta,' said deputy director of the Alipore Met office, Mihir Guha. Met officials said that Sunday's sudden drop in temperature was caused by a strong high-pressure belt over Rajasthan and Madhya Pradesh, which drove the North Wind through snow-covered Kashmir, then Uttar Pradesh and Bihar and on to Calcutta. The minimum temperature in districts like Midnapore, Bankura and Purulia have plummeted even further, compared with Calcutta. On Monday, Purulia recorded 9 degrees, Bankura 9.7 degrees and Midnapore 11.6 degrees. In Darjeeling, the minimum temperature on Monday was 9.2 degrees. 'It is still snowing in Kashmir and the minimum temperature there on Monday morning was minus 4 degrees. In Amritsar and its neighbourhood, the minimum temperature is around zero and Bihar, UP and MP are faced with a moderate cold wave. Under the circumstances, we cannot rule out another sharp drop in the minimum temperature a week from now,' an official said. Monday's minimum temperature of 14.3 degrees was a degree below normal. 'Today's temperature is nothing unusual. Around this time of the year, the minimum temperature is generally 15 degrees with a degree's upward or downward fluctuation. What is really unusual is Saturday's four-degree drop in the minimum temperature,' Guha added. He said that winter this year was, in fact, late by about five days. 'We generally have winter set in by November 20. This year, it came five days later. We usually consider the period between December 15 and January 10 as the coldest period of winter. Over the past six decades, the weather office has recorded a lowest of 7.2 degrees at Alipore in 1966 and 6.1 degrees at Dum Dum in 1945,' said Guha. The cloudless Calcutta sky now, according to deputy director Guha, is ideal for winter. The sale of sweaters picked up during the day, with people making a beeline to buy woollens at prominent city markets.