Several parts of north India reeled under severe cold and dense fog affected railway movement, with Delhi recording a minimum temperature of three degrees Celsius -- the lowest in January in two years -- making it cooler than several hill stations.

Most people kept indoors and turned to space heaters and cups of hot beverages to keep themselves warm as frosty winds from the snow-clad Himalayas barrelled through the plains, including the national capital.

Delhi's minimum temperature was lower than Dalhousie (4.9 degrees Celsius), Dharamshala (5.2 degrees Celsius), Kangra (3.2 degrees Celsius), Shimla (3.7 degrees Celsius), Dehradun (4.6 degrees Celsius), Mussoorie (4.4 degrees Celsius) and Nainital (6.2 degrees Celsius), according to official data.

Jammu and Kashmir too saw a dip in temperature, with capital Srinagar recording its coldest night of the season so far at minus 6.4 degrees Celsius on Wednesday night against minus 5.2 degrees Celsius the night before.

The India Meteorological Department (IMD) said dense fog blanketed several parts of north India and the situation would continue in the coming weeks.

At least 12 trains were delayed by one-and-a-half to six hours and two rescheduled due to the foggy weather, a Railways spokesperson said.

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 metres 'moderate', and 501 and 1,000 metres 'shallow'.

For Rajasthan, the meteorological office has issued an 'Orange Alert' for continuation of the extreme cold wave in many districts, including Alwar, Bharatpur, Dholpur, Jhunjhunu and Karauli.

It had on Wednesday issued an orange alert for Delhi-NCR for Thursday and Friday.

In Jammu and Kashmir, officials said the minimum temperature in Srinagar was also the second lowest in the month of January in the last five years.

Qazigund, the gateway town to the Kashmir Valley, registered a minimum of minus 6.2 degrees Celsius – a degree down from the previous night, they said.

The tourist resort of Pahalgam in Anantnag district, which also serves as a base camp for the annual Amarnath Yatra, registered a low of minus 9.2 degrees Celsius and was the coldest recorded place in Jammu and Kashmir.

A senior meteorologist said cold wave and temperature below normal would persist across north India, including Punjab, Haryana, Rajasthan, Uttar Pradesh and Bihar.

Day temperatures in these states are likely to remain much below normal. Cold day and severe cold day conditions are predicted to wallop Uttar Pradesh, the IMD official said.

Maximum temperatures in the state will remain 10 to 12 degrees Celsius below normal, the official said.

People in Jharkhand too witnessed chilly weather as the state was witnessing temperature hovering between 7 and 10 degrees Celsius with dense fog and cloudy sky.

All primary schools in Jharkhand will remain closed till January 8 amid the cold wave that gripped the state, according to a government notification.

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