Residents will not get any respite from the cold and fog sweeping Bihar till December 21, the India Meteorological Department (IMD) stated in its bulletin on Saturday.

The temperature in Patna slid to 9.6ºC on Saturday, the season's second lowest minimum temperature recorded. On December 11, the temperature was 8.7ºC, the lowest.

Visibility dropped to 50m on Saturday morning, slowing down life and road traffic. The IMD declared day cold condition on Saturday, implying that the minimum temperature had slid to 10ºC or below and the maximum temperature hovered 5-6 degrees Celsius below normal. The maximum temperature was 19.3ºC, five degrees below normal.

Patna Met director Sumendu Sengupta said: "Chilly winds coming from Jammu and Kashmir and Uttar Pradesh have dragged down the temperature in Patna and will continue to do so for four days."

Dipping temperature has pushed up sale of heaters, blowers and geysers. A.K. Singh, the general manager of a store on Bailey Road, said: "Our heater and geyser sale has doubled than last year. The demand for halogen heaters is so great, that they are out of stock."

Fog led to cancellation and delay of trains and flights operating from Patna. IndiGo flight 6E 652 from Delhi arrived in Patna at 1.55pm against the scheduled arrival of 10.30am. IndiGo flight 6E 367 to Delhi took off at 2.35pm against the scheduled departure of 11am. Around 26 trains originatingerminating/passing through Patna were cancelled.

Cancellation and delayed passenger trains have led to significant revenue loss for the railways.

This winter, the cancellation of Delhi-Patna Rajdhani Express from either ends has caused an estimated loss of more than Rs 50 lakh to the railways, while that of Sampoorna Kranti from both ends has caused loss of another Rs 30 lakh," said a railway official on Saturday.

Additional reporting by Ayesha Hassan