<p>A cold wave swept through Delhi on Wednesday as the minimum temperature dipped to 3.5 degrees Celsius, the India Meteorological Department said.</p>.<p>It is likely to get even colder on New Year's Eve, it predicted, as dry and icy winds barreled through the plains. </p>.<p>The Safdarjung Observatory, which provides representative data for the city, recorded a minimum of 3.5 degrees Celsius and a maximum of 16.4 degrees Celsius.</p>.<p>On December 18, Delhi had recorded a maximum of 15.2 degrees Celsius, the lowest so far this season.</p>.<p>The weather stations at Jafarpur and Lodhi Road recorded a low of 3.5 degrees Celsius and 3.7 degrees Celsius, respectively, it said.</p>.<p>During nighttime, "dense" fog reduced visibility to 50 meters in the Palam area. However, it improved to 400 meters by 9 am. The visibility at Safdarjung was 500 meters.</p>.<p>According to the IMD, "very dense" fog is when visibility is between 0 and 50 meters, 51 and 200 is "dense", 201 and 500 "moderate", and 501 and 1,000 meters "shallow".</p>.<p>In the plains, the IMD declares a cold wave if the minimum temperature dips to 4 degrees Celsius. A severe cold wave is when the minimum is 2 degrees Celsius or less.</p>.<p>Cold wave conditions are predicted in parts of the city over the next two days, it said.</p>.<p>Kuldeep Srivastava, the head of the regional forecasting centre of the IMD, said cold and dry northerly/northwesterly winds from the western Himalayas have been barreling through the plains, bringing the minimum temperature in north India down.</p>.<p>According to IMD, a cold wave is also declared when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches less than normal.</p>.<p>A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure is more than 6.4 degrees Celsius.</p>.<p>On December 20, the Safdarjung Observatory recorded a minimum of 3.4 degrees Celsius, the lowest this season so far.</p>.<p>The mean minimum temperature (7.06 degrees Celsius) in December this year so far is less than last year when it was 7.6 degrees Celsius.</p>.<p>Last year, the national capital broke the record of the longest cold spell, registering 18 consecutive cold days.</p>.<p>At 9.4 degrees Celsius, Delhi had also recorded the lowest maximum temperature in December in 119 years.</p>.<p>This year, however, the city has witnessed only three "cold" days and 7 "cold wave" days so far.</p>.<p>A cold day is declared when the maximum temperature is less than or equal to 16 degrees Celsius.</p>.<p>Delhi's air quality was recorded in the "poor" category on Wednesday.</p>.<p>The city's 24-hour average air quality index (AQI) was 290. It was 265 on Tuesday, 253 on Monday, 396 on Sunday, 337 on Saturday, 357 on Friday and 423 on Thursday.</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>Officials at the India Meteorological Department (IMD) said favourable wind speed, upto 15 kmph, aided in dispersion of pollutants.</p>
<p>A cold wave swept through Delhi on Wednesday as the minimum temperature dipped to 3.5 degrees Celsius, the India Meteorological Department said.</p>.<p>It is likely to get even colder on New Year's Eve, it predicted, as dry and icy winds barreled through the plains. </p>.<p>The Safdarjung Observatory, which provides representative data for the city, recorded a minimum of 3.5 degrees Celsius and a maximum of 16.4 degrees Celsius.</p>.<p>On December 18, Delhi had recorded a maximum of 15.2 degrees Celsius, the lowest so far this season.</p>.<p>The weather stations at Jafarpur and Lodhi Road recorded a low of 3.5 degrees Celsius and 3.7 degrees Celsius, respectively, it said.</p>.<p>During nighttime, "dense" fog reduced visibility to 50 meters in the Palam area. However, it improved to 400 meters by 9 am. The visibility at Safdarjung was 500 meters.</p>.<p>According to the IMD, "very dense" fog is when visibility is between 0 and 50 meters, 51 and 200 is "dense", 201 and 500 "moderate", and 501 and 1,000 meters "shallow".</p>.<p>In the plains, the IMD declares a cold wave if the minimum temperature dips to 4 degrees Celsius. A severe cold wave is when the minimum is 2 degrees Celsius or less.</p>.<p>Cold wave conditions are predicted in parts of the city over the next two days, it said.</p>.<p>Kuldeep Srivastava, the head of the regional forecasting centre of the IMD, said cold and dry northerly/northwesterly winds from the western Himalayas have been barreling through the plains, bringing the minimum temperature in north India down.</p>.<p>According to IMD, a cold wave is also declared when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches less than normal.</p>.<p>A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure is more than 6.4 degrees Celsius.</p>.<p>On December 20, the Safdarjung Observatory recorded a minimum of 3.4 degrees Celsius, the lowest this season so far.</p>.<p>The mean minimum temperature (7.06 degrees Celsius) in December this year so far is less than last year when it was 7.6 degrees Celsius.</p>.<p>Last year, the national capital broke the record of the longest cold spell, registering 18 consecutive cold days.</p>.<p>At 9.4 degrees Celsius, Delhi had also recorded the lowest maximum temperature in December in 119 years.</p>.<p>This year, however, the city has witnessed only three "cold" days and 7 "cold wave" days so far.</p>.<p>A cold day is declared when the maximum temperature is less than or equal to 16 degrees Celsius.</p>.<p>Delhi's air quality was recorded in the "poor" category on Wednesday.</p>.<p>The city's 24-hour average air quality index (AQI) was 290. It was 265 on Tuesday, 253 on Monday, 396 on Sunday, 337 on Saturday, 357 on Friday and 423 on Thursday.</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>Officials at the India Meteorological Department (IMD) said favourable wind speed, upto 15 kmph, aided in dispersion of pollutants.</p>