It is impossible to determine absolutely the year of least rainfall which may be expected, but evidently the longer the period over which observations have extended the nearer that end will be attained. It is sometimes assumed that the lowest annual rainfall likely to be expected in a long period of years is 80 per cent of the average annual rainfall for the same period. Or, it is sometimes assumed that the average rainfall for the lowest two or three consecutive years will be 80 per cent of the average for the entire period, and that the year of minimum rainfall may be expected to yield two thirds of the annual average precipitation. Such features will necessarily vary with the location of the district considered. Conclusions which may be true for the New England or northern Atlantic States probably will not hold for the south Atlantic and Gulf States. Data for such conclusions must be obtained from the rainfall of the locality considered. Table VI exhibits the comparative monthly rainfall which J. T. Fanning suggests may be used approximately for the average Atlantic coast districts. TABLE VI. +-----------+-----------+------------+-----------+ | | Mean | | Probable | | | Monthly | Respective | Depth in | | | Rainfall, | Ratios. | Inches of | | | Inches. | | Actual | | | | | Rainfall. | +-----------+-----------+------------+-----------+ | January | 4 × 1.65 = 6.6 | | February | 4 × 1.50 = 6.0 | | March | 4 × 1.65 = 6.6 | | April | 4 × 1.45 = 5.8 | | May | 4 × .85 = 3.4 | | June | 4 × .75 = 3.0 | | July | 4 × .35 = 1.4 | | August | 4 × .25 = 1.0 | | September | 4 × .30 = 1.2 | | October | 4 × .45 = 1.8 | | November | 4 × 1.20 = 4.8 | | December | 4 × 1.60 = 6.4 | +-----------+------------------------------------+ If the average monthly rainfall throughout the year were one inch, the values of the ratios would show the actual monthly precipitation. In general the table would be used by dividing the total yearly rainfall by 12, and then multiplying that monthly average by the proper ratio taken from the table opposite the month required. Such tables should only be used for approximate purposes and when actual rainfall records are not available for the district considered.