<P> Hail growth becomes vanishingly small when air temperatures fall below − 30 ° C (− 22 ° F) as supercooled water droplets become rare at these temperatures . Around thunderstorms, hail is most likely within the cloud at elevations above 20,000 feet (6,100 m). Between 10,000 feet (3,000 m) and 20,000 feet (6,100 m), 60 percent of hail is still within the thunderstorm, though 40 percent now lies within the clear air under the anvil . Below 10,000 feet (3,000 m), hail is equally distributed in and around a thunderstorm to a distance of 2 nautical miles (3.7 km). </P> <P> Hail occurs most frequently within continental interiors at mid-latitudes and is less common in the tropics, despite a much higher frequency of thunderstorms than in the mid-latitudes . Hail is also much more common along mountain ranges because mountains force horizontal winds upwards (known as orographic lifting), thereby intensifying the updrafts within thunderstorms and making hail more likely . The higher elevations also result in there being less time available for hail to melt before reaching the ground . One of the more common regions for large hail is across mountainous northern India, which reported one of the highest hail - related death tolls on record in 1888 . China also experiences significant hailstorms . Central Europe and southern Australia also experience a lot of hailstorms . Popular regions for hailstorms are southern and western Germany, northern and eastern France and southern and eastern Benelux . In south - eastern Europe, Croatia and Serbia experience frequent occurrences of hail . </P> <P> In North America, hail is most common in the area where Colorado, Nebraska, and Wyoming meet, known as "Hail Alley". Hail in this region occurs between the months of March and October during the afternoon and evening hours, with the bulk of the occurrences from May through September . Cheyenne, Wyoming is North America's most hail - prone city with an average of nine to ten hailstorms per season . To the north of this area and also just downwind of the Rocky Mountains is the Hailstorm Alley region of Alberta, which also experiences an increased incidence of significant hail events . </P> <P> Weather radar is a very useful tool to detect the presence of hail - producing thunderstorms . However, radar data has to be complemented by a knowledge of current atmospheric conditions which can allow one to determine if the current atmosphere is conducive to hail development . </P>

What time of year is hail most likely