Delhi swelters on a sultry day as ‘real feel’ hits 53°C

IMD’s forecast was inaccurate yet again, as no rain was recorded at any weather station in Delhi till 5.30 pm

A combination of soaring humidity levels and bright sunshine made for uncomfortably sultry conditions on Thursday, with the average Heat Index (HI) or “real feel” logging a reading of 53 degrees Celsius (°C), according to data from the India Meteorological Department (IMD).

The relative humidity oscillated between 55% and 100% in the last 24 hours, making it significantly difficult to be outdoors. (Sunil Ghosh/HT Photo)

The relative humidity oscillated between 55% and 100% in the last 24 hours, making it significantly difficult to be outdoors. The wet-bulb temperature — another indicator of thermal comfort — was 30.4°C.

IMD’s forecast was inaccurate yet again, as no rain was recorded at any weather station in Delhi till 5.30 pm. The agency had predicted light to moderate rain for Thursday.

HI, also known as the “feels like” temperature, is a calculation that depicts what the temperature feels like to the human body when relative humidity is combined with the air temperature and wind speed. It is commonly used to assess the risk of heat-related illnesses and heat stress. Prolonged exposure to an HI of 26-32°C will likely cause fatigue, while 32-40°C is widely associated with sunstroke, and 40-54°C with heatstroke.

A wet-bulb temperature of 32°C or higher makes it difficult for people to work outdoors for long. With a wet-bulb temperature of 35°C — the maximum threshold — humans can no longer regulate body temperatures.

At the Safdarjung observatory, representative of Delhi’s weather, the maximum temperature was recorded at 38.8°C — three degrees above normal. The minimum was 27.2°C, which is around normal.

The weather agency, however, predicted that a marginal relief was underway on Friday and the Capital will likely receive light to moderate showers owing to an approaching monsoon trough.

Scientists said the maximum may also drop to 36°C as gusty winds of 25-35 km/hour accompanied by rain will likely cool the surface. However, they cautioned that this will only be a slight respite as high humidity levels will persist.

“Parts of Delhi will likely receive light to moderate showers on Friday, along with gusty winds during the day. This should provide a cooling effect. Even then, humidity will remain high, as it does during the monsoon period,” said an IMD official.

Delhi’s maximum temperature was 36.4°C on Wednesday and the minimum was 27.5°C. So far this month, 56.3mm of rainfall has been recorded in the city. The normal monthly rainfall mark for July is 209.7mm. Last July, 384.6mm was recorded.

Meanwhile, Delhi’s air quality remained in the “moderate” zone. The 24-hour average air quality index (AQI) recorded a reading of 113 (moderate) at 4pm on Thursday, according to the Central Pollution Control Board. It was 138 (moderate) a day earlier at the same time. CPCB’s national bulletin showed the primary pollutants on Thursday were PM2.5, PM10 and ozone (O3).

Forecasts by the Early Warning System (EWS) for Delhi, a forecasting model under the Centre, showed Delhi’s AQI could improve to the “satisfactory” range on Friday, following a rain spell.