Why is hail a seasonal weather phenomenon?

Falling of ice pellets from the sky is called hail. The pellets can of different sizes ranging from small pea-sized to large as grape fruit size. Hail comes along with thunderstorm. Formation of hail occurs when strong currents of rising air called updrafts, carry droplets of water high enough that they freeze. The size of the hailstones depend on how strong is the updraft. Stronger the updraft, the larger the hail. It occurs during early summer, where temperatures of surface is warm enough to promote the instability associated with strong thunderstorms, but the upper atmosphere is still cool enough to support ice.

because its formation requires the strong updrafts of a thunderstorm.