Delhi saw the highest single-day rainfall in September in at least 12 years, with weather stations in the city recording 112.1 mm rainfall in 24 hours ending at 8:30 am on Wednesday.
The heavy burst of rain submerged low-lying areas in knee-deep water and affected traffic movement in parts of the city.
On an average, the capital gauges 125.1 mm precipitation in September every year, according to the India Meteorological Department (IMD).
This means that Delhi recorded 90 percent of the monthly quota of rain on the first day of the month.
Mahesh Palawat, Vice President, Skymet Weather, a private forecasting agency, said the monsoon pattern is changing due to climate change, reported PTI.
"The number of rainy days has reduced over the last four to five years in Delhi, and there has been an increase in extreme weather events," he said.
"We have been recording short and intense bouts of rains, sometimes around 100 mm rainfall in just 24 hours. In the past, this much precipitation would occur over a period of 10 to 15 days," he said.
Officials at the India Meteorological Department (IMD said the Safdarjung Observatory, considered the official marker for the city, gauged 112.1 mm rainfall in the 24 hours ending 8:30 am on Wednesday, the highest on a day in September in at least 12 years, the PTI report said.
The weather stations at Lodhi Road, Ridge, Palam and Ayanagar recorded 120.2 mm, 81.6 mm, 71.1 mm and 68.2 mm rainfall, respectively, in the 24 hours ending 8:30 am.
On Tuesday, Delhi gauged 84 mm rainfall in just six hours — between 8:30 am and 2:30 pm — that flooded roads and led to massive traffic snarls on key stretches such as ITO, Ring Road near IP Estate flyover, Dhaula Kuan, and Rohtak road.
It recorded 28 mm rainfall between 5:30 am and 8:30 am on Wednesday, officials said.
"Patchy rains are likely till late afternoon. Thereafter, the intensity will reduce. Another spell of rain is likely from September 7," an IMD official said.
The Delhi Traffic Police issued an advisory against traffic obstruction at the Azad Market Subway going towards Pratap Nagar due to the heavy waterlogging at the road. The Zakhira underpass is also closed due to waterlogging.
Weather experts said such spells of rain do not help recharge groundwater and lead to flooding in low-lying areas.
The water percolates in the ground if it rains slowly over four to five days. In case of heavy falls, the rainwater runs off quickly, Palawat said.
"The rain washes away pollutants, but since the number of rainy days has reduced, the average annual air quality is also getting affected," he said.
