<p>A cold wave swept through parts of Delhi on Monday and dense fog lowered visibility to 50 metres in some areas of the city, affecting road and rail traffic.</p>.<p>Ten trains were reported running late by 1:45 to 3:30 hours, a railway spokesperson said.</p>.<p>The Safdarjung observatory, Delhi's primary weather station, logged a minimum temperature of 5 degrees Celsius -- three notches below normal. The maximum temperature is likely to settle around 19 degrees Celsius, the weather office said.</p>.<p>On Sunday, the capital reported a cold day. According to the weather office, a cold day is when the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 degrees Celsius below normal.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/national/north-and-central/cold-conditions-intensify-across-kashmir-valley-many-places-record-lowest-temperature-this-season-1174874.html">Cold conditions intensify across Kashmir Valley, many places record lowest temperature this season</a></strong></p>.<p>The maximum temperature at Safdarjung on Sunday had settled at 16.2 degrees Celsius, five notches below normal and the lowest so far this season.</p>.<p>The mercury had dropped to 3 degrees Celsius in the Ridge area, 4.9 degrees below normal, making it the coldest place in the capital.</p>.<p>On Monday, the Ridge and the Ayanagar weather stations recorded a minimum temperature of 4 degrees Celsius and 4.1 degrees Celsius respectively.</p>.<p>Dense to very dense fog prevailed in some parts of the National Capital Region, Haryana, Punjab, west Uttar Pradesh and north Rajasthan on Monday.</p>.<p>Bathinda in Punjab and Bikaner in Rajasthan reported zero visibility, while it dropped to 50 metres and below at Ambala, Hisar, Amritsar, Patiala, Ganganagar, Churu and Bareilly.</p>.<p>Foggy conditions will persist in these areas over the next few days, the India Meteorological Department (IMD) said.</p>.<p>According to the IMD, "very dense" fog is when visibility is between 0 and 50 metres, 51 and 200 metres is "dense", 201 and 500 "moderate", and 501 and 1,000 "shallow".</p>.<p>In the plains, the IMD declares a cold wave if the minimum temperature dips to 4 degrees Celsius. A cold wave is also declared when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches below normal.</p>.<p>A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.</p>
<p>A cold wave swept through parts of Delhi on Monday and dense fog lowered visibility to 50 metres in some areas of the city, affecting road and rail traffic.</p>.<p>Ten trains were reported running late by 1:45 to 3:30 hours, a railway spokesperson said.</p>.<p>The Safdarjung observatory, Delhi's primary weather station, logged a minimum temperature of 5 degrees Celsius -- three notches below normal. The maximum temperature is likely to settle around 19 degrees Celsius, the weather office said.</p>.<p>On Sunday, the capital reported a cold day. According to the weather office, a cold day is when the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 degrees Celsius below normal.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/national/north-and-central/cold-conditions-intensify-across-kashmir-valley-many-places-record-lowest-temperature-this-season-1174874.html">Cold conditions intensify across Kashmir Valley, many places record lowest temperature this season</a></strong></p>.<p>The maximum temperature at Safdarjung on Sunday had settled at 16.2 degrees Celsius, five notches below normal and the lowest so far this season.</p>.<p>The mercury had dropped to 3 degrees Celsius in the Ridge area, 4.9 degrees below normal, making it the coldest place in the capital.</p>.<p>On Monday, the Ridge and the Ayanagar weather stations recorded a minimum temperature of 4 degrees Celsius and 4.1 degrees Celsius respectively.</p>.<p>Dense to very dense fog prevailed in some parts of the National Capital Region, Haryana, Punjab, west Uttar Pradesh and north Rajasthan on Monday.</p>.<p>Bathinda in Punjab and Bikaner in Rajasthan reported zero visibility, while it dropped to 50 metres and below at Ambala, Hisar, Amritsar, Patiala, Ganganagar, Churu and Bareilly.</p>.<p>Foggy conditions will persist in these areas over the next few days, the India Meteorological Department (IMD) said.</p>.<p>According to the IMD, "very dense" fog is when visibility is between 0 and 50 metres, 51 and 200 metres is "dense", 201 and 500 "moderate", and 501 and 1,000 "shallow".</p>.<p>In the plains, the IMD declares a cold wave if the minimum temperature dips to 4 degrees Celsius. A cold wave is also declared when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches below normal.</p>.<p>A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.</p>