The Odisha State Disaster Management Authority (OSDMA) has issued a cautionary alert for an impending heat wave across several localities in the territory. Rising temperatures, exceeding 45°C in isolated regions of Vidarbha (Eastern Maharashtra), Telangana, Andhra Pradesh and Odisha are expected this week. The ongoing monsoon and post-monsoon rainfall deficit coupled with these extreme heat conditions have led to severe water scarcity issues in Vidarbha as well as the neighbouring Marathwada region.
Understanding Heat Waves
A Heat Wave is a lengthy period of unusually high temperature, which surpasses the normal maximum temperature experienced during summer in the North-Western and South Central areas of India. These episodes are often observed between March and June, occasionally extending until July in rare instances. The affected regions’ inhabitants suffer significantly from this extreme weather as it induces physiological stress, which can be fatal in some cases. As a repercussion of climate change, daily peak temperatures are on the rise and more intense, protracted heat waves are becoming a global phenomenon.
Heat Wave Criteria by the Indian Meteorological Department (IMD)
The IMD has established certain parameters to define a Heat Wave. For plains, until the maximum temperature of a station hits at least 40°C and 30°C for hilly regions, the condition need not be recognized as a Heat Wave. When the standard maximum temperature of a station is lesser or equivalent to 40°C, a Heat Wave is defined as a deviation from normal of 5°C to 6°C, while a Severe Heat Wave is a departure of 7°C or more. If the standard maximum temperature of a station surpasses 40°C, a Heat Wave implies a variation from normal of 4°C to 5°C and a Severe Heat Wave signifies a divergence of 6°C or more. Heat waves are considered when the actual maximum temperature hits or exceeds 45°C regardless of the standard maximum temperature.
| Heat Wave Type | Normal Maximum Temp Less or Equal To 40°C | Normal Maximum Temp More Than 40°C |
|---|---|---|
| Heat Wave | Departure from Normal: 5°C to 6°C | Departure from Normal: 4°C to 5°C |
| Severe Heat Wave | Departure from Normal: 7°C or More | Departure from Normal: 6°C or More |
Health Consequences of Heat Waves
Heat Waves wield profound health impacts that generally manifest as dehydration, heat cramps, heat exhaustion and/or heat stroke. Signs and symptoms vary, with Heat Cramps typically involving Ederna (swelling) and Syncope (fainting), often accompanied by a fever below 39°C or 102°F. Heat Exhaustion is characterized by fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweatiness. Heat Stroke, the most life-threatening condition, sees body temperatures soaring to 40°C or 104°F or more, along with delirium, seizures or possibly a coma.
About India Meteorological Department (IMD)
Established in 1875, IMD operates under the Ministry of Earth Sciences of the Government of India. IMD is the chief agency tasked with meteorological observations, weather forecasting and seismology. It stands committed to providing timely and accurate weather information to the public and assisting in disaster management efforts.
