Chandigarh, Mohali and Panchkula reeled under cold wave on Wednesday as dense to very dense fog pushed the Tricity region into one of its coldest spells of the season.Chandigarh recorded a low day temperature of just 8.9 degrees Celsius, the lowest of the winter so far, plunging by a massive 6.3 degrees from Tuesday and settling 9.5 degrees below normal. The sun failed to make even a brief appearance through the day.In a striking contrast, Chandigarh remained much colder than popular hill stations, with Manali, Shimla and Srinagar recording significantly higher day temperatures of 15.2, 14.6 and 13.2 degrees Celsius respectively. The persistent fog severely reduced visibility and kept daytime heating at bay across the region.The night temperature in Chandigarh, which had dipped to a nine-year low of 2.8 degrees Celsius on Monday night, showed only marginal recovery, rising by one degree to 3.8 degrees Celsius on the intervening night of Tuesday and Wednesday. Even this was 3.1 degrees below normal and almost half of Shimla’s comparatively warmer night temperature of 7.2 degrees Celsius. Relative humidity levels remained extremely high, ranging between 86 and 95 per cent, aiding the formation and persistence of dense fog.Weather conditions over the past 24 hours remained dry. Chandigarh witnessed prolonged spells of dense fog from late night through morning, followed by mist and haze during the day and again dense fog by night.Within the region, Chandigarh logged the lowest maximum temperature at 8.9 degrees Celsius, while nearby stations such as Ambala recorded around 9 degrees Celsius. Among minimum temperatures, Hisar in Haryana was the coldest at 0.5 degrees Celsius, while Chandigarh’s minimum stood at 3.8 degrees Celsius.The India Meteorological Department has issued an orange alert for Thursday, warning of dense to very dense fog and cold wave conditions at a few places in the region. This will be followed by a yellow alert for dense fog at isolated places from Friday through next Tuesday. While the weather is likely to remain dry till January 17, light rainfall is expected at isolated places between January 18 and 20.The forecast indicates a gradual rise in minimum temperatures by about 3 to 5 degrees Celsius over the next five days, with no major change thereafter. However, fog is expected to continue disrupting normal life, especially during night and morning hours, keeping the Tricity firmly in the grip of winter’s harshest phase.21 flights cancelled, several delayed by 3-5 hrsMohali: As many as 21 flights had to be cancelled and several delayed by upto five hours due to fog and operational reasons at Shaheed Bhagat Singh International Airport here on Wednesday. Flight operations almost came to a standstill early in the morning and late in the evening. Twelve arrivals and nine departures were cancelled today. All flight arrivals after 9:20 pm had to be cancelled as a thick blanket of fog engulfed the Tricity. The international flight to Abu Dhabi scheduled for 2:40 pm, departed at 4:32 pm. The Dubai flight (4:50pm) departed at 5:38pm.