OPENING OF RAINY SEASON 37 



quarter (0.25) of an inch of rain has fallen that date be considered 

 the commencement of the rainy season. Using this then as a basis, 

 we find that the rainy season begins on October 8. The earliest 

 date of a quarter of an inch is September 8, 1884, and the latest 

 not until November 23, 1880. 



As one-quarter of an inch of rainfall at San Francisco is hardly 

 sufficient to allow of rainfall over the southern portion of the state 

 a basis of one inch at San Francisco was considered for the southern 

 portion as the commencement of the rains there, and this is found 

 to be November 1. The earliest date of one inch of rain is Septem- 

 ber 15, 1888, and the latest December 3, 1890. 



One inch of rainfall at San Francisco is not sufficient for the 

 interior of the state to allow of good plowing and seeding; hence 

 a total of two inches at San Francisco was considered, and it is 

 found that two inches of rain falls at San Francisco up to November 

 1 ; hence that date can be said to be the date of commencement of 

 good plowing. 



Five inches is considered as the rainy season being here in full 

 effect, and it is found that five inches does not fall before December 

 15, and that the earliest date that five inches has fallen is October 

 21, 1889, and the latest February 5, 1891. In this latter season 

 February was very wet, and the total for the season was seventeen 

 fifty-eight hundredths inches. 



To summarize, we have first rains September 17; rainy season 

 begins October 8, and in southern portion of state November 1 ; 

 ground moistened for plowing November 13, and rainy season in 

 full effect December 15. Of course there will be occasionally a year 

 in which a good fall of rain may come earlier and planters should 

 always be ready to take advantage of the first deep-moistening of the 

 soil to start plants which thrive in our autumn temperatures. 



The Occurrence of Frosts in California. The occurrence of 

 frost in California is, from one point of view, a purely local ques- 

 tion. As has already been stated, the frosty and the frostless places 

 are often in sight of each other on the same landscape from the 

 same point of view. It can be even more closely drawn than that. 

 It is sometimes quite as plainly to be seen as the high-water line of 

 a river flood on a sloping meadow. This occurs of course in what 

 are termed the thermal belts and is determined by elevation, air 

 currents, outflow levels and several other incidents of local topog- 

 raphy. There are often wide variations in these lines from year to 



