Northern India is experiencing an intense cold wave with dense fog, leading to "cold day" conditions and significantly below-normal temperatures. Several states, including Delhi, Uttar Pradesh, and Punjab, have seen schools close or extend winter breaks until mid-January due to the severe weather. Air quality in Delhi has also deteriorated to 'very poor' levels. The India Meteorological Department (IMD) has issued cold wave and fog alerts, warning of persistent harsh winter conditions.