The minimum temperatures in northwest and central India are likely to drop by three to five degrees Celsius over the next five days, leading to cold day conditions in Delhi and a cold wave in parts of Punjab, Haryana, Uttar Pradesh, Rajasthan, Gujarat and Maharashtra.
Cold day to severe cold day conditions are very likely over parts of Punjab, Haryana, Delhi, Uttarakhand, Madhya Pradesh, Uttar Pradesh, Rajasthan and Gujarat over the next two to three days, the India Meteorological Department (IMD) said on Monday.
Cold wave to severe cold wave is very likely in isolated pockets of Punjab, Haryana, Uttar Pradesh, Maharashtra, Rajasthan, and Gujarat over the next five days.
Dense to very dense fog is predicted in parts of Punjab, Uttar Pradesh, Rajasthan, Haryana, Delhi, Bihar, West Bengal, Odisha, Assam, Sikkim, Meghalaya and Tripura over the next two to three days, it said.
According to the IMD, a "cold day" is when the minimum temperature is less than 10 degrees Celsius and the maximum is at least 4.5 degrees Celsius below normal.
A "severe" cold day is when the maximum temperature is at least 6.5 notches below normal.
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 less than normal.
A "severe" cold wave is when the minimum temperature dips to 2 degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.
When visibility due to fog is reduced to the range of 0 to 50 metres is categorised as "very dense" fog, between 51 and 200 metres, it is "dense" fog, between 201 and 500 metres "moderate", and it is categorised as "shallow" if the visibility is between 501 and 1,000 metres.