Why does hail fall? The science of hailstorms
How layers of ice build up inside a cloud, why hail falls even in summer, the record hailstones, the effect on India's crops and how to stay safe.
Rohit Tandon · 28 October 2026 · 4 min read
Sometimes, after scorching heat, the sky suddenly turns dark and little balls of ice start drumming on the roof. Children love picking them up, but for farmers the same hail can ruin a whole crop. So why does hail fall, and where does ice come from in summer? Here is the simple science.
How do hailstones form?
Hail forms in tall thunderclouds called cumulonimbus, which can be more than 10 kilometres high. In the upper parts of these clouds the temperature is far below freezing, even when it is hot on the ground.
- Tossed upwards: fast-rising air inside the cloud carries water drops up to icy heights, where they freeze.
- Layer by layer: this small ice pellet keeps moving up and down in the cloud. Each time, a new layer of supercooled water freezes onto it, and it grows bigger.
- Falling down: when the hailstone becomes too heavy for the rising air to hold, it falls.
If you cut a large hailstone in half, you can see rings like those of an onion or a tree trunk — each layer tells the story of one "trip" inside the cloud.
Hail, snow and sleet: the difference
| What | How it forms |
|---|---|
| Hail | Solid balls of ice built up layer by layer in thunderclouds; can fall even in summer |
| Snow | Light, six-sided ice crystals formed in cold clouds; usually in winter |
| Sleet | Raindrops that freeze into small pellets as they fall through cold air |
Did you know? According to Guinness World Records, the heaviest hailstone ever recorded fell at Gopalganj in Bangladesh on 14 April 1986 and weighed about 1 kilogram. And the deadliest hailstorm on record struck Moradabad in India on 30 April 1888, killing about 246 people.
Hailstorms in India
In India hail falls most between March and May, in pre-monsoon storms, and at the end of winter with western disturbances. This is just when rabi crops such as wheat, mustard and gram are ripening, so a few minutes of hail can wipe out months of a farmer's work. Orchards and vegetables suffer badly too. The "Pradhan Mantri Fasal Bima Yojana" covers hailstorms as a localised calamity, for which the loss must be reported to the insurance company or the agriculture department within the set time. India's crop seasons: The seasons of India.
Can hail be stopped?
Some countries have tried to stop hail by spraying chemicals into clouds (cloud seeding) or with "hail cannons", but according to scientists their effect has not yet been firmly proven. The most reliable way to protect crops is still netting — in many apple orchards of Himachal Pradesh, "anti-hail nets" are stretched over the trees.
What to do in a hailstorm
- Get under a solid roof at once and stay away from windows and glass.
- If you are caught outside, cover your head and face with a bag or your hands.
- If possible, park your vehicle under a roof; if you are inside it, sit leaning away from the windows.
- Tie animals up under a roofed shelter.
- Such clouds also bring lightning — read How to stay safe from lightning.
Another extreme event of storm clouds: What is a cloudburst.
Key points
- Hail forms in tall cumulonimbus clouds.
- Layers of ice build up on hailstones as they move up and down in the cloud.
- The upper parts of the cloud are very cold, so hail falls even in summer.
- The heaviest hailstone (about 1 kg) fell in Bangladesh in 1986.
- In India hail does the most damage to rabi crops.
Frequently asked questions
Why does hail fall in the summer?
Because the upper parts of tall thunderclouds are far below freezing, even when it is hot on the ground.
Which clouds does hail fall from?
Cumulonimbus clouds.
More articles: Geography · Geography questions.
Sources
Found this useful? Share it.