Heat Waves

Heat Waves

The India Meteorological Department forecasted the “heatwave to severe heatwave conditions” over northwest, central and adjoining peninsular India along with heavy rain over northeast India.

Many parts of coastal Andhra Pradesh, Odisha and Maharashtra have also observed increase in temperatures above 42°C, triggering heatwave conditions. The heat wave has been observed due to dry northwesterly winds prevailing over northwest and central India.

India Meteorological Department

The India Meteorological Department (IMD), an agency of the Ministry of Earth Sciences, is the principal agency responsible for meteorological observations, weather forecasting and seismology in India.

Established in 1875, IMD is among the oldest weather bureaus in the world. The main objectives of IMD are:

• To establish and maintain an accurate network of meteorological instruments.
• To produce meteorological data that are relevant to societal needs.
• To organize field trips for equipping meteorological stations at various places in India with the latest technology available.
• To publish bulletins and forecasts containing synoptic, convective and sea ice products.

Heat Wave

A Heat Wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western and South Central parts of India.

Heatwaves typically occur between March and June, and in some rare cases even extend till July. India is prone to heat waves because of its position close to the tropical regions.

Higher daily peak temperatures and longer, more intense heat waves are becoming increasingly frequent globally due to climate change.

Criteria for Heat Waves

The heatwave is considered when the maximum temperature of a station reaches at least 40°C for Plains and at least 30°C for Hilly regions.

If the normal maximum temperature of a station is less than or equal to 40°C, then an increase of 5°C to 6°C from the normal temperature is considered to be a heatwave condition.

Using Zonal Modeling Technique based on the diurnal cycle and surface meteorological data with double forcing method in the process, Heatwave events have been simulated over India using the three-year data set.

If the normal maximum temperature of a station is more than 40°C, then an increase of 4°C to 5°C from the normal temperature is considered to be heat wave condition. Further, an increase of 6°C or more is considered as severe heat wave condition.

Additionally, if the actual maximum temperature remains 45°C or more irrespective of normal maximum temperature, a heat wave is declared.

Health Impacts of Heat Waves

Heat Waves are becoming more frequent and intense as the climate changes. In urban areas, they may originate from high temperatures recorded during late summer or early fall rather than from high temperatures in the summer.

The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke.

Heat health impacts include cramps, fatigue, weakness, dizziness and headaches. Children, the elderly and people with heart or lung disease are at greater risk from the heat. Heat-related illnesses can be deadly. Take simple steps to reduce your risk by wearing sunscreen, sunglasses and a hat.

The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.