EQUINOCTIAL STORM

severe storm that, in the United Kingdom and North America, is popularly believed to accompany the vernal and autumnal equinoxes. The equinoxes do not actually cause any storms, but sometimes unusually violent weather does occur at those times of the year, caused by the seasonal northward or southward shifts of air masses. The belief also may have originated with sailors who observed that West Indian hurricanes occur most often around the autumnal equinox.