Heatwave

News: According to the India Meteorological Department (IMD), there is a high likelihood of heatwave conditions in isolated areas of Odisha from March 13-17, Jharkhand from March 14-17, and Gangetic West Bengal from March 15-17. Heatwave

About Heatwave

• A heatwave is a period of unusually high temperatures over a region.
• The threshold for declaring a heatwave depends on the normal temperature in that area at a specific time of the year.
• Heatwaves mainly occur from March to June and sometimes extend into July.
• Regions affected:
  • Interior Odisha, Jharkhand, Gangetic West Bengal, South Rajasthan, North Gujarat.
  • Coastal regions also experience heat waves under specific conditions.
• Parameters measured:
  • Maximum temperature
  • Relative humidity
  • Wind speed & direction
  • Atmospheric pressure
• Climatology of maximum temperatures (1991-2020 data) is used to determine normal temperature trends. Heatwaves are then declared based on daily maximum temperature data.
• A heatwave is declared by the India Meteorological Department (IMD) when:
  • Plains: Maximum temperature reaches 40°C or more.
  • Hilly regions: Maximum temperature reaches 30°C or more.
  • Coastal areas: Temperature departure is 4.5°C or more from normal, and the actual maximum temperature is 37°C or more.

Heatwave vs. Severe Heatwave

• Based on departure from the normal temperature
  • Heatwave: When temperature departure is 4.5°C to 6.4°C from normal.
  • Severe heatwave: When departure is more than 6.4°C from normal.
• Based on actual maximum temperature:
  • Heatwave: Above 45°C.
  • Severe heatwave: Above 47°C.
• A heatwave is declared if the above conditions persist for at least two consecutive days in two or more stations of a meteorological sub-division.