India is experiencing a sharp rise in dangerously hot and humid weather, with the average number of humid summer days increasing from 101 in the 1970s to 141 days per year between 2016 and 2025, according to a new report.

The findings highlight a growing climate challenge where extreme heat is being intensified by high humidity, making conditions more stressful and potentially dangerous for millions of people.

Why Humidity Makes Heat More Dangerous

The report focuses on wet-bulb temperature, a measure that combines air temperature and humidity to show how hot conditions actually feel to the human body.

Unlike regular temperature readings, wet-bulb temperature reflects the body's ability to cool itself through sweating. When humidity levels are high, sweat evaporates less efficiently, making it harder for the body to release heat.

Researchers identified days with wet-bulb temperatures of 25°C or higher as dangerously hot and humid.

Humid Heat Is Becoming a Serious Health Threat

The increase in such days is raising concerns because prolonged exposure to hot and humid conditions can overwhelm the body's natural cooling system.

Potential health risks include:

• Heat exhaustion

• Heat cramps

• Severe dehydration

• Heatstroke

• Other life-threatening heat-related illnesses

Experts warn that even temperatures that may not appear extreme can become dangerous when combined with high humidity.

A Global Problem, Not Just an Indian One

India is not the only country witnessing this trend.

According to the analysis, the average number of dangerously humid summer days worldwide has more than doubled—from around 10 days per year in the 1970s to 23 days annually during the 2016–2025 period.

The most significant increases have been recorded in tropical and humid regions, where wet-bulb temperatures are naturally higher and can approach levels that pose serious health risks.

Climate Change Driving the Trend

The report points to human-caused climate change as a major factor behind the increase in extreme humid heat events.

Researchers estimate that approximately 64 percent of dangerously hot and humid days recorded globally since 1970 can be attributed to climate change caused by human activities.

The findings suggest that climate change has evolved from being a relatively minor influence to one of the primary drivers of increasingly severe summer conditions.

Rare Heat Events Are Becoming Common

Scientists warn that weather conditions once considered rare are now occurring more frequently in many parts of the world.

As temperatures continue to rise and humidity levels remain high, millions of people face greater exposure to dangerous heat stress, particularly in densely populated and tropical regions.

The Bottom Line

India's rising number of humid summer days highlights a growing public health and climate challenge. The combination of extreme heat and high humidity is making summers increasingly difficult and dangerous, while climate change continues to increase the frequency and intensity of these conditions. Experts say understanding wet-bulb temperature is crucial because it reflects not just how hot the air is, but how much stress that heat places on the human body.