Delhi's air quality has worsened to the 'very poor' category, with the AQI reaching 307, after a brief improvement due to strong winds. Forecasts predict this 'very poor' air quality will persist for several days. Despite the deterioration, Stage-III restrictions under the Graded Response Action Plan (GRAP) remain lifted, though Stages I and II continue. Meanwhile, Northern India is experiencing cold wave conditions and dense fog, with minimum temperatures around nine degrees Celsius, causing flight delays.