Fog Frequency in the United States

Abstract

r IHIRTY years ago the Geographical Review published a map of fog distribution over the United States, by Robert G. Stone.' Five years later a map of Average Annual Number of Days with Dense Fog appeared as one of forty-six maps depicting climates of the United States in Climate and Man, the 1941 Yearbook of Agriculture.2 No other fog maps for the entire country have since appeared, and both Stone's map and the Climate and Man map have been widely reprinted and adapted.3 A new map showing fog distribution over the conterminous United States, based on averages at 251 first-order Weather Bureau stations through 1960, is presented here as Figure 1. Stone's map (Fig. 2) was based on mean values for the full period of record ... (through 1931 or 1932) ... for 410 stations in all, including many non-Weather Bureau observatories and about loo stations outside the United States proper. His primary basic were 30-year means, 1901-1930, for 108 United States stations and 26 Mexican stations; in addition, data were obtained from about 5oo lighthouses.4 The Climate and Man map (Fig. 3) was based on 200 first-order Weather Bureau stations, period 1899-1938.