Why Delhi Is Heating Faster Amid India’s Heatwave Alerts

Delhi experienced its highest temperature of this season on April 23, with the Ridge recording 43 degrees Celsius, according to the India Meteorological Department (IMD).

On April 20, the met department had predicted that the national capital will see temperatures around 40 degrees Celsius on April 20, alongwith issuing a yellow alert for heatwave conditions later in the week, which has now taken effect. The IMD had predicted heatwaves on Friday and Saturday as the temperature was predicted to increase further.

While the national capital braces for rising heat, other parts of India may see rain and thunderstorms.

Reasons Behind Delhi’s Heat

According to reports, Delhi’s temperature is rising rapidly due to a combination of seasonal and local factors. Clear morning skies allow intense solar radiation to heat the surface quickly, while urban materials like concrete trap and amplify this heat.

As the sun’s angle increases in late March–April, this effect intensifies, pushing temperatures higher earlier in the day.

Highlighting the factors behind increased frequency of Heatwaves in India, Vishwas Chitale, Fellow, Council on Energy, Environment and Water (CEEW) said that a combination of long-term climate change and local urban factors could be the reasons. "On the one hand, global warming is steadily increasing baseline temperatures. On the other hand, rapid urbanisation is creating dense, concrete-heavy landscapes that trap heat and prevent cooling," he underscored, adding, "As a result, nearly 57% of Indian districts, home to about three-fourths of the population, are already at high to very high heat risk. We are also seeing a worrying rise in warm nights—over 70% of districts have experienced at least five additional warm nights in the last decade (2012–2022) compared to the 1982–2011 baseline, with cities being particularly affected."

In additon, he mentioned that cities can act immediately by scaling solutions that are already proven under Heat Action Plans. This includes strengthening heat-health early warning systems, setting up accessible cooling centres, and protecting outdoor workers in the short term. He further said that, alongside these urgent steps, cities must invest in long-term measures such as expanding tree cover, adopting cool roofs, restoring water bodies and ensuring shaded public spaces, adding that preparing for heat now requires a coordinated approach that combines immediate response with sustained urban planning interventions.

States Under Heatwave Alert

Heatwave conditions are expected over large parts of central and northern India. According to the India Meteorological Department (IMD), these states include Madhya Pradesh, Chhattisgarh and Vidarbha, along with Uttar Pradesh, Rajasthan, West Bengal, Jharkhand, Punjab, Haryana and Odisha. These regions are expected to experience sustained high temperatures over the next few days.

Southern states such as Kerala, Tamil Nadu, Puducherry, Andhra Pradesh and Karnataka are also likely to face hot and humid conditions, adding to overall discomfort.

The IMD has also warned of warm night conditions in Haryana, Chandigarh, Uttar Pradesh and Odisha. This means temperatures will remain elevated even after sunset, offering little relief from the daytime heat.

Heatwave Criteria in India

A heatwave is a time when temperatures are much higher than normal for a certain area. Because of this, the temperatures at which heatwaves are declared vary from place to place based on the historical temperatures of that area. Heatwaves are worse when there are other weather conditions that make them worse, like high humidity, high wind speed and long heatwave events.

For plains, a heatwave is considered when the temperature rises to 40 degrees Celsius or higher in flat areas and 30 degrees Celsius or higher in hilly areas. When temperatures are 4.5 to 6.4 degrees Celsius above normal, a heatwave is declared. When the difference is more than 6.4 degrees Celsius, a 'severe heatwave' is declared.

A heatwave is declared when the temperature reaches 45 degrees Celsius or higher, and a severe heatwave is declared when the temperature reaches 47 degrees Celsius or higher. According to IMD, the criteria must be met in at least two stations within a meteorological subdivision for two consecutive days, with the declaration made on the second day.

For coastal areas, slightly different rules apply: a heatwave may be declared when the temperature is at least 4.5 degrees Celsius above normal, provided the actual maximum reaches 37 degrees Celsius or more.

Urban Heat and Risks

According to the 2024 report published by Social and Policy Research Foundation, Delhi's urban heat islands result from intense concretisation and rapid green cover loss.

These hotspots make nighttime temperatures much higher and raise health risks like dehydration and heat stroke. Extreme heat also poses a threat to the economy, as it could cut outdoor workers' productivity by a significant 15% by 2050.

Staying Safe During Heatwaves

According to the Apollo website, staying safe during a heatwave requires a mix of hydration, diet, and limited exposure. Health advisories recommend drinking plenty of water and fluids like coconut water or buttermilk to prevent dehydration. Avoid stepping out during peak afternoon hours, wear loose cotton clothing and eat light, water-rich foods while avoiding caffeine, alcohol and heavy meals.

Keeping indoor spaces cool, taking frequent breaks, and recognising early symptoms like dizziness or fatigue are also critical to preventing heat-related illnesses.