In News: Many districts in Rajasthan, Haryana, Uttar Pradesh, Madhya Pradesh have been posting temperatures over 45 degrees Celsius or five degrees above what is normal.
What is Heat wave ?
- Heat wave is considered if the maximum temperature of a station reaches at least 40°C or more for Plains, 37°C or more for coastal stations and at least 30°C or more for Hilly regions.
Following criteria are used to declare heat wave:
- a) Based on Departure from Normal
- Heat Wave: Departure from normal is 4.5°C to 6.4°C
- Severe Heat Wave: Departure from normal is >6.4°C
- b) Based on Actual Maximum Temperature (for plains only)
- Heat Wave: When actual maximum temperature ≥ 45°C
- Severe Heat Wave: When actual maximum temperature ≥47°C
To declare a heat wave, the above criteria should be met at least in 2 stations in a Meteorological subdivision for at least two consecutive days and it will be declared on the second day.
Impact of Heat Wave Warning
|Nil||Comfortable temperatures||No cautionary action required|
|Heat wave conditions at|
district level, likely to
persist for 2 days
|Heat is tolerable for general public but moderate health concern for vulnerable people e.g. infants, elderly, people with chronic diseases.||Avoid heat exposure|
|i. Severe heat wave conditions likely to persist for 2 days.|
ii. With varied severity, heat wave is likely to persist for 4 days or more.
|Increased likelihood of heat illness|
symptoms in people who are either
exposed to sun for a prolonged period or doing heavy work.
High health concern for vulnerable people e.g. infants, elderly, people with chronic diseases.
|Avoid heat exposure– keep cool. Avoid dehydration|
|i. Severe heat wave likely to persist for more than 2 days.|
ii. Total number of heat/severe heat wave days likely to exceed 6 days.
|Very high likelihood of developing heat illness and heat stroke in all ages.|
|Extreme care needed for vulnerable people.|