The Western Highlands of Kenya in Africa.
In terms of annual downpour, Kericho in Kenya has more hail than anywhere else on earth, since it
falls on average 132 days each year. By comparison, the UK averages only fifteen hail-days in a year
and the worst affected area in the US, the eastern Rockies, experiences an average of forty-five haildays
What causes the abundance of hail is not fully understood. Kericho is the home of Kenya’s tea
plantations, and a 1978 study showed that organic litter from the tea plants gets stirred into the
atmosphere, where it acts as a nucleus around which hailstones can grow.
Another theory is that the high altitude of the region could be to blame, as the shape of the terrain
causes a large uplift of warm air which quickly condenses. This, and the reduced distance between
the freezing level (about 3 miles up) and the ground, reduces the chance of hailstones melting.
The average hailstone is about quarter of an inch across, but they can grow large enough to dent
cars, shatter greenhouses and even injure people.
The largest single hailstone ever recorded in the United States was 7 inches in diameter, 18.75
inches in circumference, and weighed in at just under a pound. It fell into the back yard of a house in
Aurora, Nebraska, in June 2003. This is off the end of the official US scale for describing hailstones
which starts at ‘pea’ and rises progressively through ‘mothball’, ‘walnut’ and ‘tea-cup’ to ‘softball’.
The Aurora hailstone was the size of a small melon and would have hit the ground at 100 mph.
Hail costs the US a billion dollars each year in damage to property and crops. A hailstorm that
struck Munich, Germany, in July 1984 caused an estimated billion dollars’ worth of damage to trees,
buildings and motor vehicles in a single afternoon. Trees were stripped of their bark and whole fields
of crops were destroyed. Over 70,000 buildings and 250,000 cars were damaged and more than 400
people were injured.
However, the world’s worst hailstorm occurred in the Gopalanj district of Bangladesh on 14 April
1986. Some of the hailstones weighed over two pounds and at least ninety-two people were killed.