Imperial, California short periods of time. The precipitation in the winter months is predominantly rain showers from the occasional winter storms. At times these storms bring cold temperatures to Imperial and surrounding cities, and mountain snowfall to the nearby mountains. Snow is almost totally unknown in the city, except for a powerful winter storm that covered the entire valley with 4 inches snow on December 12, 1934 and a very brief fall of sleet mixed with hail during a shower in December 1967. On average there are about 11 days that dip into the mid to lower 30s. In January, the normal
Hail . GR is derived from the French word grêle. Smaller-sized hail, as well as snow pellets, use the coding of GS, which is short for the French word grésil. Terminal velocity of hail, or the speed at which hail is falling when it strikes the ground, varies. It is estimated that a hailstone of in diameter falls at a rate of , while stones the size of in diameter fall at a rate of . Hailstone velocity is dependent on the size of the stone, friction with air it is falling through, the motion of wind it is falling through,