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Record heat has gripped India since March. It’s about to get worse.

March maximum temperatures were the highest in 122 years. Temperatures late this week could near April records.

High temperatures simulated by the American GFS model in India on April 23. (WeatherBell)
Comment

Temperatures in India remain high amid ongoing heat waves that have plagued the country with dry, sweltering weather since early spring. The India Meteorological Department (IMD) stated that its March maximum temperatures were the highest in nearly a century and a quarter, and rainfall was only running about a quarter to a third of normal.

A hot weather pattern has persisted in many parts of India during April, and the highest temperatures yet may afflict the country Wednesday into the weekend.

A large majority of Indian households live in poverty and lack air conditioning, increasing the population’s vulnerability to heat. Older adults are especially at risk from high temperatures.

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The sky-high temperatures exemplify the overlap between natural variability and the effects of human-caused climate change, which are known to make heat waves more intense and prolonged.

Another heat wave on the way

On Monday, several cities across the nation registered highs over 109 degrees (42.8 Celsius); the city of Wardha in the west-central state of Maharashtra soared to 113 degrees (45 Celsius).

Temperatures are forecast to rise further, leaping 10 to 15 degrees (5.5 to 8.3 Celsius) above average during the second half of this week, reigniting worry for those without any way to escape the heat. Portions of northern and western India, especially areas near the borders with Pakistan and Nepal, may endure the most extreme heat. That’s where highs may reach 110 to 115 degrees (44 to 46 Celsius) Wednesday and Thursday.

Between Friday and Sunday, temperatures could climb as high as 120 degrees (49 Celsius) if the most extreme forecast models are correct.

Temperatures may approach national records in India and Pakistan for the month of April. According to Maximiliano Herrera, an expert on world weather extremes, the highest reliable April temperature in India is 118.9 degrees (48.3 Celsius), set in Barmer in northwest India in 1958. Nawabshah, Pakistan, about 125 miles inland from the Arabian Sea, hit 122.4 degrees (50.2 Celsius) four years ago; this record, possibly the highest temperature ever observed worldwide in April, may be more difficult to beat.

A contributor to the heat is high pressure at the middle altitudes in the atmosphere, a dome-like “ridge” of sinking air that eradicates cloud cover and deflects storm systems to the north. That will allow sunshine to pour in unobstructed, heating the antecedent dry air. Overarching weather patterns suggest little relief in sight over the week to 10 days ahead, although the intensity of the heat may ease some next week.

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A summerlike spring in India

India’s average maximum temperature during the month of March was 91.6 degrees (33.1 Celsius), narrowly surpassing the previous record from March 2010.

Fifteen Indian states and territories have been affected by heat waves since March, according to the Center for Science and Environment, a public interest research and advocacy organization based in New Delhi. The states of Rajasthan and Madhya Pradesh in northwest and central India were hardest hit; each having observed 25 heat wave days so far this spring.

At least one person died of heat-related causes in March in Maharashtra, while two others died after being struck by lightning.

During April alone, New Delhi, home to more than 25 million people, has hit 100 degrees (37.7 Celsius) 23 out of 25 days; the average high temperature is about 98 degrees (36.7 Celsius).

All told, the capital’s running about 4.8 degrees (2.7 Celsius) above average for the month. Delhi posted a 107-degree (41.7 Celsius) high on four April days, and nicked 108 (42.2 Celsius) on April 19.

Potentially more problematic than the lofty high temperatures, though, have been elevated nighttime lows. That’s especially true in the city, where the “urban heat island” effect spurred by cement and paved-over surfaces traps thermal energy long after the sun has set. Warm overnight lows prevent the body from having a nocturnal cool-down period, increasing heat stress and the propensity for negative health effects.

Delhi’s average nighttime low during April is 71 degrees (21.7 Celsius). Seven nights in April have failed to dip below 75 degrees (23.9 Celsius).

Since the start of March, Delhi has only received 0.01 inch of rain. The average for March and April is 1.14 inches. The drought reinforces the heat, since dry air is easier to heat up, which then saps the ground of moisture further and entrenches the cycle.

Rainfall across the country has been 71 percent lower for March 2022 than its long-term average. The IMD stated that rainfall over India has been its third-lowest since 1901.

Neighboring Pakistan had the highest worldwide positive temperature anomaly during the month of March, meaning the margin between observed temperatures and averaged temperatures there was bigger than anywhere else across the globe. Multiple stations set all-time monthly records during February and March.

Temperatures during that heat wave peaked a dozen or more degrees above average.

Increasing temperatures in India

In 2020, the IMD’s Ministry of Earth Sciences published a report citing a 1.3-degree (0.7 Celsius) rise in temperatures across India as a whole between 1901 and 2018.

Under an extreme emissions scenario, it projects the frequency of summer heat waves to at least triple by the end of the century. It also cautions that the frequency of warm nights is projected to jump by 70 percent.

Ordinarily, temperatures begin to plateau and acutely decline late in the spring during the buildup of the summer monsoon, which occurs when onshore winds transport copious moisture northward and bring heavy downpours across much of the region. However, that too is changing.

“The overall decrease of seasonal summer monsoon rainfall during the last 6-7 decades has led to an increased propensity for droughts over India,” the ministry writes. It projects “a high likelihood of increase in the frequency (>2 events per decade), intensity and area under drought conditions in India” by the end of the century.

Jason Samenow and Kasha Patel contributed to this report.

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