Heat Wave

What is a 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 parts of India. Heat Waves typically occur between March and June, and in some rare cases even extend till July. The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

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Criteria for Heat Wave

IMD has given the following criteria for Heat Waves:

• Heat Wave need not be considered till maximum temperature of a station reaches atleast 40^oC for Plains and atleast 30^oC for Hilly regions
• When normal maximum temperature of a station is less than or equal to 40^oC Heat Wave Departure from normal is 5^oC to 6^oC Severe Heat Wave Departure from normal is 7*C or more
• When normal maximum temperature of a station is more than 40^oC Heat Wave Departure from normal is 4^oC to 5^oC Severe Heat Wave Departure from normal is 6^oC or more
• When actual maximum temperature remains 45^oC or more irrespective of normal maximum temperature, heat waves should be declared. Higher daily peak temperatures and longer, more intense heat waves are becomingly increasingly frequent globally due to climate change. India too is feeling the impact of climate change in terms of increased instances of heat waves which are more intense in nature with each passing year, and have a devastating impact on human health thereby increasing the number of heat wave casualties.
• Higher daily peak temperatures and longer, more intense heat waves are becomingly increasingly frequent globally due to climate change. India too is feeling the impact of climate change in terms of increased instances of heat waves which are more intense in nature with each passing year, and have a devastating impact on human health thereby increasing the number of heat wave casualties.

Health Impacts of Heat Waves

• The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke. The signs and symptoms are as follows:
• Heat Cramps: Ederna (swelling) and Syncope (Fainting) generally accompanied by fever below 39^oC ie 102^oF.
• Heat Exhaustion: Fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweating.
• Heat Stoke: Body temperatures of 40^oC ie 104^oF or more along with delirium, seizures or coma. This is a potential fatal condition

Do's and Dont's

What to do during a Heat Wave

• Recognise the signs of heat stroke, heat rash or heat cramps such as weakness, dizziness, headache, nausea, sweating and seizures.
• Drink water and oral hydration drinks
• Rest in shade, take breaks if you must work in the sun
• Place a cool, wet cloth on your head to cool off
• Check on neighbours and elderly family to ensure they are keeping cool
• Wear light and loose clothes
• Use an umbrella or hat or cover head with a cloth

What not to do during a Heat Wave

• Do not go out in the direct sun
• Avoid extensive physical activity
• Do not send children or pets out in the sun or leave them in closed vehicles.
• Do not consume caffeinated drinks (like aerated drinks) and alcohol during extreme heat
• Avoid wearing dark, heavy or tight clothing
• Avoid cooking during peak heat hours. If you must cook, open doors and windows to ventilate the cooking area adequately.

Recover and Build

If you think someone is suffering from the heat:

• Move the person to a cool place under the shade
• Give water or a rehydrating drink (if the person is still conscious)
• Fan the person
• Consult a doctor if symptoms get worse or are long lasting or the person is unconscious
• Do not give alcohol, caffeine or aerated drink
• Cool the person by putting a cool wet cloth on his/her face/body
• Loosen clothes for better ventilation

Emergency Kit

• Water bottle
• Umbrella/ Hat or Cap / Head Cover
• Hand Towel
• Hand Fan
• Electrolyte / Glucose / Oral Rehydration

Source: National Disaster Management Authority (NDMA), Government of India