• When the most extreme (day) temperature for an area in the fields crosses 400 Celsius, it is called a heatwave. The extent of the temperature is 300 Celsius over the hilly regions
• When the day temperature shoots up by 4 to 5 degrees above the normal maximum temperature, it is announced as a heatwave
• It takes place chiefly from March to June and in some rare cases even in July. Heatwaves are at their peak in May, which is the hottest month in India. It causes physiological strains which can be fatal 

Heatwave effects on humans:

Prolonged explore to extreme heat can cause:

• Heat cramps
• Heat strokes
• Death
• Worsen underlying chronic disorders such as different respiratory, brain, and cardiovascular problems

Criteria for Heat Waves:

• The temperature of 45°C or 46°C is a heatwave condition. And further temperature increase of 7°C or more from the average temperature is considered a severe heat wave condition
• Heatwaves should be declared when the maximum temperature remains 45°C or more irrespective of the average maximum temperature
• NDMA has framed national guidelines for executing the calamity plan – “prevention and management of heatwaves” to give a framework for implementing, coordinating, and evaluating extreme heat waves-related activities
• It gives the instructions to limit the effect during the heatwave and to forestall genuine affliction or demise as a result of hotness stroke:
  • Going out in the Sun should be avoided, especially between 12.00 noon and 3.00 p.m
  • Drinking sufficient water and frequently, even if not thirsty.
  • Wearing light-weight, loose, porous cotton and light-coloured clothes
  • Carry water while travelling
  • Use an umbrella, hat, protective goggles, and footwear while going out in the sun
  • Working outside and strenuous activities should be avoided when the temperature outside is high (especially between 12 noon and 3 p.m.)
  • Avoid drinking dehydrating things like tea, coffee, alcohol, and carbonated soft drinks
  • One must consume rehydrating drinks such as lassi, ORS, or lassi
  • Avoid eating high-protein food and stale food
  • A hat or an umbrella should be used while working outside, and to cover your head, neck, face, and limbs, a damp cloth should be used
  • Keeping the home cool by using curtains, shutters, sunshades, and open windows at night
  • The usage of fans and baths from cold water must be increased
  • The guidelines also list long-term mitigation measures to be undertaken by states/local authorities in respective areas to address the issues at a broader level. NDMA also organises workshops annually in collaboration with heat-prone states to further strengthen the preparedness by bringing all stakeholders to one platform. The joint efforts of stakeholders have significantly brought down the deaths by heatwaves

Heat Wave Action Plan:

• It aims to provide a framework for implementation, evaluation, and coordination to reduce the impact of extreme heat events
• The focus is on alerting the population at risk due to heatwaves and taking appropriate precautions for the vulnerable sections like the elderly, children, and pregnant women
• It provides scope for modifications at the local level depending upon the meteorological conditions, society’s capacity, and the administration’s capability
• NDMA plays a critical role in guiding the states and the union government, continuously modifying the plan and research through the National Institution for Disaster Management (NIDM)

Issues and Way Forward:

• Currently, the Government of India doesn’t recognise heatwaves as a natural disaster under the National Disaster Management Act, 2005. Therefore, the Government does not devote financial and infrastructure resources to the issue
• Huge diversity in the impact of heatwaves across geography makes it further challenging to devise an integrated strategy
• The central Government has to put resources and aid into cities and states to prepare for the heatwave emergency by evolving and implementing Heat Code and Heal Action Plans (HAPs)

The current IMD definition of a heatwave is based only on temperature, which most scientists believe is insufficient to capture heat stress. The Heat Code should also define the Standard Operating Procedure to be activated during intense heat, like restrictions on working hours and facilities for relief at public places and hospitals.

Conclusion

In conclusion, we can state that a heatwave occurs when the highest (day) temperature for an area in the fields exceeds 400 degrees Celsius. While in hilly regions, the temperature reaches 300 degrees Celsius in the hilly areas. A heatwave mostly occurs when the daytime temperature rises by 4 to 5 degrees above the normal maximum temperature. And occurs primarily from March to June, and in rare cases, even in July. Lastly, it causes physiological strains that can lead to death.