Why Delhi Is Baking: Dry Westerlies, Moist Sea Winds And A Delayed Monsoon

Delhi reeled under intense heat on Tuesday, with the "feels like" temperature soaring to 53.5 degrees Celsius at 5.30 pm, even as actual temperatures across the city stayed around 40-41 degrees Celsius at major stations, according to the India Meteorological Department (IMD).

The intense discomfort is being driven by dry westerly winds from Pakistan, which are keeping temperatures high, while southwesterly winds from the Arabian Sea are also reaching Delhi and increasing humidity, experts said.

The Science Behind The Temperature

The interaction between these dry and moist air masses leads to cloud formation, but there is not enough moisture for widespread rainfall. By the time clouds develop, usually around 4 or 5 pm, the day's maximum temperature has already been recorded, causing both the actual temperature and the "feels like" temperature to remain unusually high.

According to IMD readings, Safdarjung recorded 40.5°C, while Palam touched 41.0°C, Lodhi Road stood at 40.1°C, and Ayanagar also recorded 40.1°C. The Ridge station was the hottest at 41.5°C, with temperatures ranging 2-4.8 degrees above normal across stations.

Delhi's Warmest June in Two Years

The prolonged heat spell has pushed Delhi's minimum temperature to record levels. On Sunday, the city recorded its warmest June morning in two years, with the minimum temperature settling at 31.1 degrees Celsius, 3.2 degrees above normal. The last time the city's minimum temperature was higher was on June 14, 2024, when it was recorded at 33.3 degrees Celsius.

Humidity levels have ranged between 37 and 70 per cent during the day, making outdoor conditions especially dangerous. The city also experienced dangerous wet-bulb temperatures peaking at 29.5°C — a metric that measures the body's ability to cool itself via sweat. A sustained wet-bulb reading past 32°C makes outdoor physical labour highly hazardous.

Heatwave Criteria and IMD Alert

Despite the oppressive conditions, the IMD has issued a Yellow Alert for Delhi-NCR, predicting a shift in weather patterns with strong surface winds of up to 50 kmph, dust storms, and isolated pockets of very light to light rain or thunderstorms expected to cross the region.

According to the weather office, a heatwave has been realised over Delhi, and the heat index, or 'feels-like' temperature at 5.30 pm was around 50.7 degrees Celsius. The IMD has forecast a partly cloudy sky with a spell of very light to light rain or thunderstorms towards the afternoon or evening for Monday.

Monsoon Delay Worsens Conditions

The IMD said in a release that conditions are favourable for further advance of the southwest monsoon into some more parts of the North Arabian Sea and some areas of Uttar Pradesh and Uttarakhand, among other states, during the next two to three days. It is likely to continue its movement over some more parts of Uttar Pradesh, Uttarakhand, some areas of Himachal Pradesh, Jammu and Kashmir, Ladakh and southeast Rajasthan during the subsequent two to three days.