One moment the sky is dark and the wind is picking up; the next, small white balls of ice are bouncing off roofs, cars and fields. A hailstorm can last only five to fifteen minutes, but in that short time it can shred a vegetable crop, flatten wheat that is ready for harvest, dent cars and break windows. Many people are surprised to see ice falling from the sky on a warm afternoon — and that surprise is a good starting point for understanding what actually causes hail.
This guide explains how hail forms, why some storms produce it and others don't, when and where hailstorms are most common in India, and what you can do to protect yourself, your home and your crops.
What Is Hail?
Hail is precipitation in the form of balls or irregular lumps of ice, called hailstones, that fall from thunderstorm clouds. Meteorologists generally call ice pellets hail when they are about 5 mm in diameter or larger. Most hailstones in India are the size of a pea or a marble, but strong storms can produce stones as large as a lemon.
If you cut a large hailstone in half, you will often see rings — alternating clear and milky-white layers, a bit like an onion. Those layers are the record of the hailstone's journey through the storm, and they are the key to understanding how hail forms.
What Causes Hailstorms? The Science in Simple Steps
Hail needs three ingredients: a tall thunderstorm cloud, strong updrafts and plenty of supercooled water. Here is how they work together.
1. A towering thunderstorm cloud forms
Hail only comes from cumulonimbus clouds — the tall, dense thunderstorm clouds that can reach heights of 10 to 15 km or more. These clouds form when warm, moist air near the ground rises rapidly into colder air above. The more unstable the atmosphere, the faster the air rises and the taller the cloud grows.
2. Updrafts lift raindrops above the freezing level
Inside the cloud, powerful rising currents of air called updrafts carry water droplets upward. A few kilometres above the ground, the temperature drops below 0°C. Surprisingly, many droplets don't freeze immediately — they stay liquid even at temperatures well below zero. This is called supercooled water.
3. A small ice "embryo" starts to grow
When a tiny ice particle or frozen drop meets supercooled droplets, those droplets freeze onto it on contact. This seed of ice — the hail embryo — begins to grow as it is carried around the cloud.
4. The hailstone grows layer by layer
As the hailstone moves through different parts of the cloud, it grows in two ways:
- Clear layers form in regions with lots of supercooled water, where droplets freeze slowly and spread out before freezing, leaving clear ice.
- Milky or opaque layers form where droplets freeze instantly, trapping tiny air bubbles that make the ice look white.
A hailstone may be swept up and around inside the storm, or simply held in place by a strong updraft for several minutes, collecting more and more ice.
5. The hail falls when it gets too heavy
Once the hailstone becomes too heavy for the updraft to support — or it drifts out of the strongest updraft — it falls. The stronger the updraft, the longer the stone can stay aloft and the larger it can grow. That is why the biggest hail comes from the most violent thunderstorms.
Why Does Hail Fall on Hot Days?
It seems strange, but hot weather near the ground actually helps hail form. Strong surface heating makes the lower atmosphere unstable, and that instability drives the powerful updrafts that hail needs. Meanwhile, the freezing level is still several kilometres above the ground, so the ice can grow up there no matter how warm it is at street level.
Whether the hail reaches the ground depends on its size and the depth of warm air it falls through. Small stones may melt completely and arrive as heavy, cold rain. Larger stones fall fast enough to reach the surface as ice. This is why hail is less common in very hot, humid coastal areas, where the freezing level is high and the warm layer is deep, and more common in the northern plains, the plateau regions and the hills.
When and Where Do Hailstorms Occur in India?
Late winter: western disturbance hail (February–March)
In North and Central India, many hail events in late winter are linked to western disturbances — the eastward-moving weather systems that bring winter rain and Himalayan snow. When a strong western disturbance draws in moisture and meets cold air aloft, thunderstorms with hail can break out over Punjab, Haryana, Rajasthan, Uttar Pradesh, Madhya Pradesh and parts of Maharashtra. This timing is especially damaging because the rabi crop is near harvest.
Pre-monsoon: thunderstorm season (March–May)
As temperatures climb, the land heats strongly and the atmosphere becomes very unstable. Severe thunderstorms with hail occur across the plains, the eastern states and the Northeast. Locally known spring storms in the east, such as the Kalbaisakhi (Nor'westers) of West Bengal, Odisha and Assam, often bring hail along with squally winds and lightning.
Hill states
Jammu & Kashmir, Himachal Pradesh and Uttarakhand see hail in spring and early summer, which is a major concern for apple, cherry and stone-fruit orchards.
Hail is rarer during the main monsoon months, when the atmosphere is very moist and the freezing level is high, and in the coastal regions of the far south.
Hail vs Sleet vs Graupel
- Hail: Hard, layered ice balls from thunderstorms, usually 5 mm or larger. Falls in short, intense bursts.
- Graupel: Soft, small, crumbly white pellets, formed when snowflakes collect a coating of frozen droplets. Common in the hills during cold showers and often mistaken for small hail.
- Sleet: Usually refers to raindrops that freeze into small, clear ice pellets while falling through a cold layer near the ground, or to a mix of rain and snow.
How Hailstorms Damage Crops and Property
For farmers, a single hailstorm can wipe out months of work. Hailstones tear leaves, break stems, knock grain out of ears of wheat, and bruise or split fruit. The damage is often worst when the crop is close to harvest:
- Wheat and barley may lodge (fall flat) and lose grain.
- Mustard, gram and lentil pods can shatter.
- Vegetables such as tomato, cauliflower and leafy greens can be badly torn.
- Orchards — apples, pears, plums, mangoes and grapes — can suffer bruised, scarred or fallen fruit that loses its market value.
In towns and cities, larger hail can dent vehicles, crack windscreens, damage solar panels and greenhouses, and break skylights. The strong winds and lightning that come with hail-producing storms add to the risk.
Hailstorm Safety: What You Should Do
Before the storm
- Check the forecast and alerts, especially in February–May. Thunderstorm warnings that mention hail are a signal to prepare.
- Park vehicles in a garage or under solid shelter. A thick blanket or car cover can reduce damage if no shelter is available.
- Bring pets and livestock under cover, and move potted plants and outdoor items indoors.
During the storm
- Stay indoors and keep away from windows, glass doors and skylights.
- If you are driving, slow down and, if it is safe, stop under a solid structure. Do not stop under trees, hoardings or electric lines. Stay in the car, turn your back to the windows and cover your head.
- If you are caught outside, find the nearest sturdy building. If there is none, crouch down and protect your head and neck with your arms, a bag or a jacket.
- Remember that lightning is often the bigger danger — the same rules as for any thunderstorm apply.
After the storm
- Watch for slippery, ice-covered surfaces and fallen branches.
- Photograph damage to crops, vehicles and property for insurance claims.
- Farmers should report crop losses to the local agriculture office promptly, as crop insurance schemes usually require claims to be filed within a short window.
How Farmers Can Reduce Hail Losses
- Follow forecasts closely in the weeks before harvest and, where possible, harvest promptly once the crop is mature rather than leaving it standing in the field.
- Anti-hail nets are widely used in hill orchards to physically shield fruit trees.
- Crop insurance is the most important financial protection against hail, which is a localised calamity that can hit one village and spare the next.
- After a hailstorm, follow advice from the local Krishi Vigyan Kendra (KVK) on recovery steps such as nutrient sprays or replanting short-duration crops.
Can Hail Be Forecast?
Forecasters can predict the conditions that favour hail — strong instability, moisture, cold air aloft and wind patterns — a day or two in advance, and official thunderstorm warnings in India often mention hail for specific regions. However, hail falls in narrow streaks, so it is impossible to say days ahead exactly which village or field will be hit. Short-range nowcasts, based on Doppler weather radar, give the most precise warnings, usually one to three hours ahead. Radar can detect the intense echoes that indicate large ice inside a storm.
You can keep an eye on the local forecast for your own town or village on TodayWeather's location pages, which show hourly conditions, rain probability and the multi-day outlook.
Key Takeaway
Hailstorms are caused by strong thunderstorms with powerful updrafts that lift raindrops high into freezing air, where they grow layer by layer into balls of ice until they are heavy enough to fall. In India they are most common from February to May, linked to western disturbances in late winter and to pre-monsoon thunderstorms in spring. Because hail strikes quickly and in small areas, the best protection is to watch forecasts and nowcasts, take shelter indoors, protect vehicles, and — for farmers — combine timely harvest, protective nets where practical, and crop insurance.
