Delhi recorded its hottest day of the season on Thursday, with temperatures crossing the 40°C mark at the city’s main weather station. At the same time, air quality worsened into the ‘poor’ category, leading authorities to reimpose restrictions under the Graded Response Action Plan (GRAP), nearly a month after they were lifted.

Heat likely to intensify

According to the forecasts, temperatures in Delhi are likely to rise further and could reach up to 42°C by Friday. Earlier in the week, maximum temperatures were recorded at 40.3°C, which was 3.5°C higher than average at the Safdarjung observatory. Across the city, the maximum was registered at 41.4°C at the Ridge observatory located in northern Delhi.

This increasing trend has been observed consistently in the past few days. On Wednesday, Thursday, Monday, and Sunday, Delhi witnessed temperatures of 39.1°C, 38.2°C, 36.1°C, and 34.7°C, respectively. The primary cause for such warming can be attributed to clear skies and lack of Western Disturbance in the area since April 7–8.

Air quality worsens

The air quality index stayed at the “poor” level for the second successive day and deteriorated even further during the day on Friday, increasing from 204 to 226. The reason behind the deterioration is the excessive amount of dust in the region, causing an increase in PM10 pollution.

According to the forecasts, the air quality may continue to fluctuate within the “moderate” and “poor” levels for the coming seven days. Consequently, the CAQM has once again imposed GRAP Stage 1 measures in the NCR with immediate effect.

These measures are mostly preventive and include steps like increased water sprinkling, use of mechanised road sweepers, improving public transport frequency, and strict monitoring of waste dumping and industrial emissions.

“The Sub-Committee accordingly takes the call to invoke the 31-point action plan as per stage-I of the extant Grap in the entire NCR, to avoid further deterioration of air quality in the region,” said the CAQM.

Earlier relief now reversed

The restrictions related to the GRAP policy were lifted on March 16 following improvement in the air quality, which became moderate. The air quality index since then stayed within the 'moderate' zone with improvements to satisfactory levels when it rained.

According to the IMD, the temperature will continue to be high, between 40°C to 42°C during the coming weekends, even when a western disturbance begins affecting the western Himalayas region starting from Thursday.

“Some thundery development may occur towards late evening or night-time in Delhi on Friday. However, rain is unlikely here. The day will remain hot with the maximum expected to remain over 40°C,” said an IMD official.