Dense fog prevailed across several districts of Uttar Pradesh and persisted till late hours during the day, leading to cold day conditions in many parts of the state, the Met department said on Friday.
Meteorological officials attributed the situation to the influence of westerly winds passing through north India.
As a result, maximum temperatures in several areas fell significantly below normal over the past 72 hours, while minimum temperatures remained largely unchanged.
According to the forecast, similar weather conditions are likely to continue over the next 24 to 48 hours, with dense to very dense fog and cold day to severe cold day conditions expected in around 40 districts of the state.
A gradual rise in temperature and reduction in fog intensity is likely thereafter with the influence of an approaching western disturbance.
The Met Centre, Lucknow, has issued red and orange alerts for several districts.
Areas likely to witness very dense fog are -- Kaushambi, Prayagraj, Fatehpur, Pratapgarh, Varanasi, Jaunpur, Ghazipur, Azamgarh, Mau, Ballia, Gorakhpur, Basti, Kushinagar, Maharajganj, Siddharthnagar, Balrampur, Shravasti, Bahraich, Lakhimpur Kheri. -- PTI