New Delhi, Jan 4 (IANS): As the cold wave continued to hit the national capital, the India Meteorological Department (IMD)'s forecast showed the minimum temperature dropping to 7 degrees Celsius on Thursday.

As of 8:30 a.m., the minimum temperature recorded was 7.7 degrees Celsius, with shallow to moderate fog.

The IMD classifies fog intensity into four types: shallow, moderate, dense and very dense fog. The visibility ranges from 999 m to 500 m, 499 m to 200 m, 199 m to 50 m and less than 50 m, respectively.

On Thursday, the city recorded lowest visibility of 500 m at Palam and Safdarjung at 8:30 a.m.

IMD's visibility outlook for the next subsequent 12 hours says that it may likely improve to 1500m from 8 a.m., and may reduce to 1000m from 4 p.m.

The IMD further predicted the maximum temperature to hover around 17 degree Celsius.

According to Indian Railways, 26 trains are behind their scheduled arrival time, and the extent of delay varies across multiple routes due to fog and cold wave.

The highest delay reported in trains arriving in Delhi is six hours.

The air quality continued to remain in 'very poor' category at several stations across the city.

At the Anand Vihar area, PM2.5 levels were recorded to be in 'severe' category standing at 414 and PM10 reached 358 or ‘very poor’, according to the Central Pollution Control Board (CPCB).

The Air Quality Index (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'.

The Indira Gandhi International (IGI) Airport T3 also witnessed PM2.5 levels at 340, the ‘very poor’ category while the PM10 was at 222, falling under the 'poor' category, respectively.