Parts of Delhi reeled under a "severe" cold wave and "dense" fog on Thursday as the minimum temperature dropped to 1.8 degrees Celsius, the India Meteorological Department (IMD) said. Visibility levels dropped to 100 meters at Palam and 201 meters at Safdarjung due to "dense" to "moderate" fog in the morning, an IMD official said.
"Dense" fog is predicted in parts of the city on Friday as well. According to the IMD, "very dense" fog is when visibility is between 0 and 50 metres. In case of "dense" fog, visibility is between 51 and 200 metres, "moderate" 201 and 500 metres, and "shallow" 501 and 1,000 metres.
The Safdarjung Observatory, which provides representative data for the city, recorded a minimum of 2 degrees Celsius, five notches below normal, as against 3.2 degrees Celsius on Wednesday. The maximum temperature settled at 19.2 degrees Celsius. The weather stations at Jafarpur, Lodhi Road and Ridge recorded a minimum of 1.8 degrees Celsius, 2.4 degrees Celsius and 3.6 degrees Celsius, respectively.
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. Cold and dry northerly/northwesterly winds from the western Himalayas have been barrelling through the plains, bringing the minimum temperature in north India down, Kuldeep Srivastava, the head of the IMD's regional forecasting centre said.
On January 1, the city had recorded a minimum of 1.1 degrees Celsius, lowest for the month in 15 years. Delhi had been registering above-normal minimum temperatures till Monday, as a cloud cover persisted over the city under the influence of successive Western Disturbances.
However, the temperature started dropping with the commencement of cold northwesterly winds after the withdrawal of the latest WD. The city's minimum had settled at 4.8 degrees Celsius on Tuesday, 7 degrees on Monday, 7.8 degrees Celsius on Sunday, 10.8 degrees Celsius on Saturday, 9.6 degrees Celsius on Friday and 14.4 degrees Celsius on Thursday, the highest in January in four years, according to IMD.