Record heat in Iran raises global concern as heat index touches 82 degrees

This summer is far from ordinary across the globe. Following a record-setting season in India, concerns have now shifted to Iran, where a troubling report has surfaced. Last week, a weather station near Dayrestan Airport in southern Iran recorded a heat index of 82.2 degrees Celsius and a dew point of 36.1 degrees Celsius. 

If verified, these figures could set new records for the highest heat index and dew point ever documented on Earth, according to a post by US-based meteorologist Colin McCarthy on X (formerly Twitter).

For reference, staying in temperatures with a heat index of 40-54 degree Celsius for too long can lead to a heatstroke.

The dew point is the temperature at which the air becomes fully saturated with moisture, leading to condensation. When the body overheats, it sweats to cool down, but if high humidity prevents sweat from evaporating, the body struggles to cool itself, making the temperature feel even hotter.

However, McCarthy has questioned the accuracy of these readings. He noted that nearby weather stations reported significantly lower dew points, emphasising that an official investigation is necessary to confirm the accuracy of these measurements.

The extreme readings, resulting from an air temperature of 38.9 degrees Celsius combined with 85 per cent relative humidity in a village in southern Iran, have sparked concerns and demands for an official investigation, as indicated by data released by the US National Weather Service.

What is the heat index?

The heat index, also known as apparent temperature, indicates how hot it feels to the human body when relative humidity is factored in with the actual air temperature. It reflects the combined effects of temperature and humidity, offering a clearer understanding of how the weather will feel.

For instance, high humidity can make temperatures feel hotter than they are because sweat doesn't evaporate as easily, making it harder for the body to cool down. In contrast, lower humidity allows sweat to evaporate more efficiently, making the air feel cooler than the actual temperature. The heat index is especially relevant in summer or tropical climates where high temperatures and humidity can lead to heat-related health risks such as heat exhaustion or heatstroke.

In drier regions, temperatures might be higher, but the lower humidity makes the air feel cooler.

Extreme heat in West Asia

During the Hajj pilgrimage in Saudi Arabia, the heat claimed over 1000 lives. More than 200 Indian pilgrims died during the Hajj pilgrimage 2024, with a majority of the deaths being attributed to cardio-respiratory and cardio-pulmonary arrests, the government informed the Lok Sabha.

The temperatures soared to 51.8 degrees Celsius in Mecca on June 17 this year, making it extremely difficult for the approximately 1.8 million people, many elderly and frail, to participate in the days-long, predominantly outdoor pilgrimage.

In response to the severe heat, authorities in Iran and neighbouring countries have issued warnings, urging residents to take precautions against heat-related illnesses. The Middle East, already grappling with conflicts, is now facing an unprecedented heatwave, with temperatures approaching 50 degrees Celsius in Iraq and Iran. This extreme heat has also triggered widespread power outages.

Delhi's summer reached 50 degrees

In June this year, Delhi endured a prolonged period of intense heat, with the capital experiencing persistently high temperatures. The IMD reported that the national capital recorded a heat index of 51 degrees Celsius.

Several regions in northwest India consistently saw maximum temperatures of 40 degrees Celsius or higher daily for over a month, marking this heatwave as the most intense since 1951 for Delhi and neighbouring states.

IMD data also revealed that on June 18, Delhi experienced its warmest night on record, with a minimum temperature of 35.2 degrees Celsius, which was eight degrees above the normal range.

The heatwave that gripped Delhi from June 11 to 19 claimed the lives of 192 homeless individuals, making it the deadliest on record for this period, according to a report by the NGO Centre for Holistic Development.