The India Meteorological Department (IMD) has issued a severe heat wave warning for parts of Uttar Pradesh, Bihar, Himachal Pradesh, Haryana, Chandigarh, Delhi, and Punjab. As northwest India faces unprecedented heat this summer, isolated pockets in Jammu, Uttarakhand, Rajasthan, Madhya Pradesh, and Jharkhand are also likely to experience heatwave conditions tomorrow.

The IMD’s weather map indicates a swath of red from Punjab to Bihar, highlighting the severe conditions. Minimum temperatures are currently between 28-33 degrees Celsius, which is 3 to 6 degrees above normal for the plains of Northwest and Central India.

Environmental expert Sunita Narain has emphasized the urgent need for a heat index, akin to the air quality index (AQI), to help people understand the health impacts of heat and take necessary precautions. She stresses that heat is not just about high temperatures but also humidity, which can exacerbate heat stress.

Heat stress occurs when the body cannot cool itself effectively, leading to symptoms like dizziness, headaches, and potentially life-threatening conditions such as organ failure. This can happen due to prolonged exposure to heat and other environmental factors that affect the body's ability to regulate its temperature.

The IMD has been issuing an experimental heat index since April last year and plans to introduce a more comprehensive system called the "heat hazard score." This new metric will consider multiple parameters, including temperature, humidity, wind, and duration of heat exposure.