Not 51 Degrees Celsius, But Feels That Hot: What's Behind Delhi's Heat

Delhi has been reeling under an intense heatwave. The India Meteorological Department (IMD) said the city's actual maximum temperature was 41.3 degrees Celsius, which is 4.1 degrees Celsius higher than the normal temperature for this time of the year.

However, what grabbed attention was the "real feel," or heat index, of 51.3 degrees Celsius. This does not mean Delhi's air temperature has reached this point. Instead, it means that because of high humidity, the weather felt as hot as 51.3 degrees Celsius to the human body.

The reason it feels much hotter is because of a weather measurement called the wet-bulb temperature. The IMD also recorded a wet-bulb temperature of 29.77 degrees Celsius. Humidity in Delhi remained very high, ranging from 35% to 63% throughout the day.

The weather department said humidity will remain high for the next few days, so Delhi's weather is likely to stay hot, humid and sticky.

What is wet-bulb temperature?

Wet-bulb temperature measures the combined effect of heat and humidity. When humidity is high, sweat does not evaporate easily from the skin, making it harder for the body to cool itself. This is why people feel much hotter than the actual air temperature.

For example, if the air temperature is 44 degrees Celsius with high humidity, it may feel like 50-51 degrees Celsius.

Why does Delhi feel so muggy right now?

Usually, Delhi's summer heat is dry, which means the air has very little moisture. But currently, southwesterly winds from the Arabian Sea are bringing moisture to northwestern India, according to weather experts.

At the same time, the monsoon has not yet reached Delhi. Normally, the monsoon brings rain from the Bay of Bengal, which helps cool the weather. Since the rains have not arrived yet, the city is getting humid without enough rain.

When will Delhi get relief from the heat?

The India Meteorological Department (IMD) has predicted that rain and thunderstorms may return on June 29, when the temperature is likely to stay between 29 degrees Celsius and 39 degrees Celsius.

The weather is expected to remain similar on June 30, with the maximum temperature around 38 degrees Celsius and the minimum around 28 degrees Celsius.

The monsoon is expected to reach Delhi after July 4.