lO BULLKTIN 85 



than 80 per cent of the possible amount of sunshine. Data compiled by 

 the Phoenix office of the Weather Bureau shows that for the period 

 from 1905 to 1916 the lowest recorded temperature was 16° while the 

 highest was 117°. 



The growing season is longer than in almost any other irrigated 

 district. Reports of the United States Weather Bureau show that the 

 growing season, that is, the season between killing frosts, is approxi- 

 mately ten months at Phoenix. 



There is a fairly wide variation in extreme winter temperatures in 

 certain portions of the Valley. The areas having the highest altitudes 

 lying near the foothills are of course less subject to frost. In fact, the 

 frost risk in certain of these favorably located districts is so small that 

 citrus groves have been a decided commercial success. There is no 

 area in the entire Valley which can be considered as strictly frost proof 

 but the risk in what might be termed the citrus belt is not too great for 

 commercial success. In general, climatic conditions in the Salt River 

 Valley have admitted of a very great diversification of production. Prac- 

 tically all of the staple crops which have ever been grown under irri- 

 gated conditions can be produced in this section successfully. The ex- 

 treme length of the growing season coupled with the hot summers and 

 mild winters have permitted the growing of certain important special 

 crops whose success is dependent upon climatic conditions. There is 

 perhaps no more favorable location in the United States for the produc- 

 tion of long staple cotton. Dates bear abundantly and many of the 

 finer varieties seem to find the Salt River Valley a natural habitat. 

 Olives, figs and citrus fruits are successful by reason of the compara- 

 tively mild winters. 



An annual rainfall of slightly more than eight inches is distributed 

 rather irregularly throughout the year, the least occurring in April, 

 May and June and the heaviest in July. Rains occur occasionally dur- 

 ing the winter months. The comparatively small rainfall makes it pos- 

 sible to produce and cure alfalfa hay of excellent color. Occasional 

 unexpected rains during the spring and early summer months cause 

 some damage to both hay and grain. It so happens that the rainiest 

 season of the year is coincident with the harvesting period for canta- 

 loupes. The problem is not as serious practically as it appears from 

 casual observation. There have been, however, some decided losses of 

 melons caused by unwelcome rainfall. A rain during the cantaloupe 

 picking season may result in many of them cracking open in the field 

 and considerable quantities of those which appear superficially to be 



