<p>Delhi's minimum temperature rose slightly to 5.5 degrees Celsius on Monday under the influence of a fresh Western Disturbance affecting the upper reaches of the Himalayas. </p>.<p>“This a fast-moving Western Disturbance (WD) and it will withdraw on Tuesday. Thereafter, the temperatures are expected to drop again,” Mahesh Palawat, an expert at Skymet Weather, a private forecasting agency, said. </p>.<p>The WD will lead to a light to moderate snowfall in the upper reaches of Jammu and Kashmir, Ladakh and Himachal Pradesh, he said. </p>.<p>The India Meteorological Department said the Safdarjung Observatory recorded a minimum of 5.5 degrees Celsius on Monday morning as against 3.4 degrees Celsius on Sunday, the lowest this season so far.</p>.<p>It has predicted cold wave conditions at some place in the city from December 23 to December 26.</p>.<p>Moderate to dense fog is also predicted during the period, it said.</p>.<p>For the plains, the IMD declares a cold wave when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches less than normal for two consecutive days.</p>.<p>However, for small areas such as Delhi, a cold wave can be declared if the criteria is fulfilled even for a day, officials said.</p>.<p>The air quality was recorded in the "very poor" category. </p>.<p>The city's air quality index (AQI) was 323 at 10 am. The 24-hour average AQI was 321 on Sunday.</p>.<p>An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".</p>
<p>Delhi's minimum temperature rose slightly to 5.5 degrees Celsius on Monday under the influence of a fresh Western Disturbance affecting the upper reaches of the Himalayas. </p>.<p>“This a fast-moving Western Disturbance (WD) and it will withdraw on Tuesday. Thereafter, the temperatures are expected to drop again,” Mahesh Palawat, an expert at Skymet Weather, a private forecasting agency, said. </p>.<p>The WD will lead to a light to moderate snowfall in the upper reaches of Jammu and Kashmir, Ladakh and Himachal Pradesh, he said. </p>.<p>The India Meteorological Department said the Safdarjung Observatory recorded a minimum of 5.5 degrees Celsius on Monday morning as against 3.4 degrees Celsius on Sunday, the lowest this season so far.</p>.<p>It has predicted cold wave conditions at some place in the city from December 23 to December 26.</p>.<p>Moderate to dense fog is also predicted during the period, it said.</p>.<p>For the plains, the IMD declares a cold wave when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches less than normal for two consecutive days.</p>.<p>However, for small areas such as Delhi, a cold wave can be declared if the criteria is fulfilled even for a day, officials said.</p>.<p>The air quality was recorded in the "very poor" category. </p>.<p>The city's air quality index (AQI) was 323 at 10 am. The 24-hour average AQI was 321 on Sunday.</p>.<p>An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".</p>