Delhi recorded the hottest day of the year on Sunday as the mercury touched 32.8 degrees Celsius. The day temperature is likely to rise further over the next few days, but a western disturbance, which may cause very light rain on Friday, is expected to bring down the mercury. Delhi’s air quality deteriorated on Sunday and entered the poor range of the Air Quality Index (AQI) The AQI was 209 at 4pm, compared to 158 in the moderate range a day earlier. The Commission for Air Quality Management imposed measures under Stage I of the Graded Response Action Plan (GRAP) on Friday after AQI turned poor. The minimum temperature on Sunday was 13.5 degrees Celsius, a degree below normal, at Safdarjung, the city’s base station. It was 31.1 degrees Celsius on Saturday, before Sunday, the highest maximum temperature was recorded on Feb 27 at 32.4 degrees Celsius and Pitampura was the second hottest station on Sunday.