After two days of dense to very dense fog, visibility in the city improved to 350 metres at Palam and Safdarjung at 5.30am, against 25 and 50 metres a day earlier. However, there was little relief from the biting cold. The maximum temperature settled at 21.2 degrees Celsius, the lowest so far this season, against 23.2 degrees the previous day. The minimum was recorded at 7.1 degrees Celsius, a notch below normal, against 6.3 degrees a day earlier. Very dense fog in Indo-Gangetic plains disrupted road traffic and delayed 18 trains. IGI airport officials said although operations remained normal and low visibility procedures were active between 12am and 4am, three flights had to return from Amritsar, Lucknow and Varanasi due to low visibility.