Delhi saw just 10 rainy days in August; air quality worsened

New Delhi, Aug 31: Delhi recorded just 10 rainy days in August, the lowest in seven years, and a cumulative rainfall of 214.5 mm, lower than the average of 247 mm, according to the India Meteorological Department (IMD).

Nearly two-thirds of the total rainfall (138.8mm) was recorded in a single day, August 21. It was also the highest downpour in a day in August in 14 years.

Experts have attributed the uneven distribution of rainfall to climate change.

The national capital had recorded 237 mm rainfall and 18 rainy days in August 2019. There were 16 such rainy days in the corresponding period in 2018 and 19 in 2017.

The fewer number of rainy days also had an impact on the air pollution levels in the city.

Delhi recorded "moderate" air quality on 20 days this month, the highest in four years. There were just 11 days of "satisfactory" air quality this time as compared to 27 in August last year, according to Central Pollution Control Board data.

The capital did not record a single "good" air day this month, while there were four and two such days in 2020 and 2019, respectively.

August, the rainiest month of the year, records the maximum number of "satisfactory" air quality days, weather experts said.

The city witnessed a prolonged "break monsoon" phase from August 9 to 18, the longest in four years. It again entered a partial "break monsoon" phase from August 24 to 28, said Mahesh Palawat, vice-president (Meteorology and Climate Change), Skymet Weather, a private forecasting agency.

During the monsoon season, there are spells when the trough shifts closer to the foothills of the Himalayas, leading to sharp decline in rainfall over most parts of the country. This is called a "break monsoon" phase.

However, rainfall increases along the foothills of Himalayas, northeast India and parts of the southern peninsula.

Overall, Delhi has recorded 756.4 mm rainfall since June 1, when the monsoon season starts, against a normal of 523.8 mm.

Four districts in Delhi have recorded "deficit" rainfall, while five have gauged "excess" or "large excess" precipitation so far this monsoon season, according to IMD data.

North Delhi has received 849.2 mm rainfall, which is 90 per cent more than normal, while Northeast Delhi has recorded 263.8 mm rainfall against an average of 560.2 mm since June 1, a shortfall of 53 per cent.

The national capital had recorded 34.8 mm rainfall against a normal of 65.5 mm in June. In July, it received 507.1 mm rainfall, which was nearly 141 per cent above the long-period average of 210.6 mm. It was also the maximum rainfall in the month since July 2003, and the second-highest ever.

Despite the monsoon embracing Delhi only on July 13, making it the most-delayed in 19 years, the capital had recorded 16 rainy days in the month, the maximum in the last four years.

The IMD measures monsoon performance in five categories -- large excess (rainfall above 60 per cent of normal), excess (20 per cent to 59 per cent more than average), normal (minus 19 to 19 per cent of normal), deficit (minus 20 per cent to minus 59 per cent) and large deficit (60 per cent below normal).