What exactly is a Heatwave?, why they happen, & how you can stay safe

The India Meteorological Department (IMD) recently issued a yellow alert for several parts of North and Central India. Cities in Uttar Pradesh, Madhya Pradesh, Rajasthan, and Haryana are under warning, while states like Gujarat, Tamil Nadu, and Maharashtra are facing extreme heat and humidity. The alerts will remain in place until at least April 25.

Across India, temperatures are rising rapidly even before May begins. In Telangana, districts like Nirmal and Adilabad are already touching 44°C and beyond. The IMD-Hyderabad has placed the state under an orange alert from April 24 to 26. Similar alerts are active in Delhi, Odisha, and parts of Bihar, where daytime temperatures are hovering above 43°C. The intense heat is raising serious concerns about health and safety.

A north-south trough in the atmosphere is adding to the problem. This weather system is disrupting normal patterns and increasing the intensity of the heat. As a result, people across India are facing one of the earliest and harshest summer waves in recent years. With temperatures soaring and humidity rising, it’s essential to understand what a heatwave is—and how to protect ourselves.

What exactly is a Heatwave?

A heatwave happens when temperatures stay unusually high for several days in a row. It’s not just about a hot day—it’s when the heat lasts long enough to affect people’s health, agriculture, and daily life. In India, the IMD defines a heatwave based on temperature thresholds that vary by region, but generally, anything above 40°C is considered dangerous.

The impact of a heatwave depends on how much higher the temperature is than normal. For example, in plains areas, a heatwave is declared when the temperature is 4.5°C to 6.4°C above the usual average. If the temperature jumps more than 6.4°C, it’s classified as a severe heatwave. These conditions can become deadly, especially for children, the elderly, and people with health issues.

Heatwaves are silent disasters. They don’t cause dramatic damage like floods or storms, but they can be even more dangerous. Prolonged exposure to high heat can cause heat exhaustion, dehydration, heatstroke, and even death. That’s why it’s important to take them seriously—even if the sun seems calm.

Why do heatwaves happen?

Heat waves occur when a high-pressure system stalls over an area for several days. This system traps warm air, causing temperatures to rise steadily. The skies stay mostly clear, allowing the sun to heat the ground continuously. Without wind or rain to cool the air, the heat builds up and stays locked in.

Climate change is making heat waves more frequent and intense. As global temperatures rise, heatwaves are starting earlier in the season and lasting longer. Scientists say that regions like South Asia, especially India, are becoming more vulnerable due to urbanisation, deforestation, and rising greenhouse gas emissions.

In India, other weather patterns can also add to the heat. For example, when a western disturbance passes through the north or when a trough develops from north to south, it can disrupt normal cooling processes. This year, such patterns are playing a major role in driving up temperatures across states like Telangana, Madhya Pradesh, Delhi, and Odisha.

How you can stay safe?

The most important step during a heatwave is to stay hydrated. Drink plenty of water even if you don’t feel thirsty. Avoid tea, coffee, and alcohol, as they can dehydrate your body. Coconut water and lemon water with a pinch of salt are good options to replace lost minerals.

Try to stay indoors during the hottest part of the day, usually between 12 noon and 4 PM. If you must go outside, wear light-colored, loose-fitting clothes and cover your head with a hat or scarf. Use an umbrella or a damp cloth on your neck to stay cool. Avoid heavy exercise during peak heat hours.

Keep an eye on vulnerable people—children, the elderly, and those with medical conditions. Make sure they are drinking enough fluids and staying cool. If someone shows signs of heat exhaustion—such as dizziness, headaches, or vomiting—move them to a shaded area, give them fluids, and seek medical help immediately.

Government Initiatives

While many government responses to heatwaves often rely on short-term fixes, there are efforts underway to build better long-term solutions. The National Disaster Management Authority (NDMA) has issued clear guidelines to reduce the impact of heatwaves across India. These include regular public advisories, early warning systems, and the development of Heat Action Plans (HAPs) at the state and city levels.

Several cities like Ahmedabad and Nagpur have already implemented local heat action plans. These plans focus on improving health services, training healthcare workers, and informing the public about heat safety. Local governments work with meteorological departments to spread warnings through TV, radio, and mobile alerts.

But managing heatwaves needs more than alerts. It requires strong policies, city planning that includes green spaces, better housing designs, and long-term awareness campaigns. While personal precautions are important, collective action, smart planning, and government accountability are key to protecting lives as heatwaves become more common and more dangerous. Staying alert, prepared, and involved can make a real difference.

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