Hail is basically rain which has been thrown up and down in a strong storm, freezing in the higher portions of the storm, dropping lower to get coated in more rain, then being thrown higher to freeze again. Hail is generally small - often around the size of a pea - but hail has been recorded as big as footballs. Large hail is common in the Great Plains of the US, where it can cause millions of dollars of crop and property damage. Hail is not to be confused with sleet, or ice pellets, which are basically frozen raindrops. Hail is charactarized by its association with strong thunderstorms and is common on hot summer days - it does not need to be cold to hail. Most areas see occasional hail, I've seen enough hail to color the ground white here in California a few times.