Delhi’s driest monsoon in 3 years withdraws, rain deficit 19%: Met

Published on Oct 02, 2022 06:03 PM IST

Delhi received just 516.9mm rainfall this monsoon, well below the normal mark of 639.7mm and the lowest since 2019, when the Capital got just 404.3mm of rain, showed data from the weather office. To be sure, IMD classifies overall monsoon rainfall 19% above or below the average as ‘normal’.

Rain at Delhi’s Connaught Place. (File)
Rain at Delhi’s Connaught Place. (File)

The India Meteorological Department (IMD) on Thursday declared that the south-west monsoon has withdrawn from Delhi, leaving the city with a 19% rainfall deficit for the season.

Delhi received just 516.9mm rainfall this monsoon, well below the normal mark of 639.7mm and the lowest since 2019, when the Capital got just 404.3mm of rain, showed data from the weather office. To be sure, IMD classifies overall monsoon rainfall 19% above or below the average as ‘normal’.

The city got 1,169.7mm rain last monsoon and 576.6mm in 2020, according to IMD records.

This year, much of Delhi’s monsoon rain was concentrated in just two strong spells on either end of the season.

The monsoon arrived on June 30 this year with 117.2mm of showers recorded in a 24-hour window until 8:30 am on July 1 (the most in a day this year) and departed after a nearly continuous three-day spell of rain between September 22 and 25, which saw Delhi get 106mm of rain.

The Capital, in effect, got just 293.7mm of rain on all the other days of the monsoon this year, leaving the city with prolonged dry spells that saw temperatures and humidity hit uncomfortably high levels. Experts said this was largely because the monsoon trough stayed south of Delhi for much of the rainy season.

Mahesh Palawat, vice-president at Skymet, a private weather forecaster, said, “With the monsoon trough mostly staying south of Delhi, the Capital only received rain in a transitory period, when the trough moved northwards or towards the foothills. Due to this, we saw substantial periods of no rain or just drizzles,” he said.

Showers also saw vast variations across districts, showed data from IMD, with East Delhi receiving 30% more rain (868.2mm against an average of 666.4mm) than it usually does all season, even as North-East Delhi got 55% less rain (301.6mm against an average of 666.4mm) than normal. This too was likely behaviour of the monsoon trough, said experts.

“When the trough is away and there is some moisture is being fed to an area through easterly winds, convective rainfall occurs more commonly and that is what happened to Delhi largely this season. When convective rains take place, thunderclouds form locally within a matter of hours due to high temperature and adequate moisture. These rain spells are short but can be intense. Depending on where these clouds form, these districts can have more rain,” said Palawat.

East Delhi was the only district where rainfall was in ‘excess’, showed the data, while it was ‘normal’ in four districts (Central, North, South and South-West), and in a ‘deficit’ four others (New Delhi, Northeast, North-west and West).

IMD did not have data for Shahdara and South-East districts.

This was also the city’s fourth driest monsoon over the past decade, showed records from the weather office. In 2014, Delhi received just 370.8mm of rainfall, in 2019, it was 404.3mm and in 2015, it was 515.3mm. In comparison, the highest rainfall Delhi received during this period was 1169.7mm, which Delhi received last year.

Rainfall between -99% and –60% is classified as a ‘large deficit’, between –59% and –20% is classified as a ‘deficit’, between –19% and 19% is classified as ‘normal’ rainfall, between 20% to 59% as ‘excess’ and over 60% as ‘large excess’.

While the Met department classifies June as a monsoon month, it recorded just 24.5mm of rain — a deficit of 67%, compared to a normal of 74.1mm.

July ended with 286.3mm of rainfall, an excess of 37% against a normal mark of 209.7mm. August, which is normally Delhi’s wettest month, received only 41.6mm of rainfall – a large deficit of 82% against a monthly normal of 233.1mm. September was following a similar trajectory, until the late spell of showers pushed the rain reading into the ‘excess’ zone.

RK Jenamani, scientist at IMD said conditions, over the past few days, became favourable for the south-west monsoon to withdraw from parts of northwest India.

“Delhi already began to see a dry spell over the last couple of days, and this will now continue for the next four days as well. Some rain is now expected on October 4 and on October 5. The northwesterly winds blowing at present will switch to easterly-southeasterly winds then, bringing moisture,” he said.

Meanwhile, Delhi on Thursday recorded a maximum temperature of 33.9 degrees Celsius (°C), a degree below normal for this time of the year and a minimum of 23.3°C, around the normal mark.

The city is likely to enjoy clear skies on Friday, even though the maximum and minimum temperatures are expected to inch up to 35°C and 23°C respectively.

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