A Test for the Period of 18 Cycles per Year in Rainfall Data

Abstract A number of different analyses are used to examine 63 years of daily United States rainfall data to determine whether a suggested periodicity of 18 cycles per year exists. Although a slight tendency was found for such a period to persist in phase during the 63 years, the amplitude is extremely small. On the basis of the several tests performed we conclude that there is no reality to a periodicity at or near 18 cycles per year.