FIRE-SEASON FORECASTS ON A CALIFORNIA FOREST 



By R. W. Ayres^ 



One of the chief reasons why each fire season is looked upon 

 without pleasiu-e and with more or less fear is because of the 

 uncertainty of what the summer months have in store. It is true 

 that for certain matters, such as the peak of the fire season, the 

 nimiber of men needed on the suppression force and their length 

 of employment, and the areas of the greatest hazard, we have made 

 long strides towards foretelUng what will happen. But still there 

 is left the one all important question: "What kind of a fire season 

 is it going to be?" 



The nimiber of fires, the acreage burned and the length of the 

 season belong to the prophet, rather than the forecaster, but there 

 are other questions which have a prospect of being solved by the 

 study of meteorological data. For instance, it is reasonable to 

 suppose that a very wet winter and spring would mean a fire sea- 

 son that would begin late and would not be so intense as a dry one. 

 The summer temperature should be some indication of the char- 

 acter of the fire season. And perhaps the danger from lightning 

 could be determined by weather conditions. Of course, there are 

 only a few years — ^much too few — to work with, and there may be 

 factors overlooked which contain the key to the problem. 



To begin with, it will be assumed that the season which fol- 

 lowed the largest precipitation would be the best from a fire pro- 

 tection point of view, and will coimt the precipitation as beginning 

 with the end of the previous fire season, so none will be lost. That 

 is, for 1911 we will count the rainfall from October, 1910, to June, 

 1911. Listing the seasons in this way, and leaving out all years 

 previous to 1911, they run as follows: 



Year 



No. 1 1911 42.3 inches 



No. 2 1914 38.4 " 



No. 3 1915 37.8 " 



No. 4 1912 19.6 " 



No. 5 1913 17.5 " 



This rainfall is taken in Sonora, elevation 1,875 feet, which 

 corresponds to the most dangerous part of the Forest. These 



^Forest Supervisor, Stanislaus National Forest. 



595 



