CLIMATIC CONDITIONS IN OREGON. 



By H. M. Williamson, Secretary of State Board of Horticulture. 



(All figures relating to temperature and rainfall, and most of 

 those giving elevations in this article are from the publications of the 

 Oregon Section of the Climatological Service of the Weather Bureau 

 of the U. S. Department of Agriculture, Edward A. Beals, district 

 forecaster and section director, Portland, Oregon. For fuller details 

 as to climatic conditions in this State, address Oregon Section, U. S. 

 Weather Bureau, Portland, Oregon.) 



From the nature of a large number of inquiries which come to the 

 office of the State Board of Horticulture, it is apparent that many 

 persons who live east of the Rocky Mountains have a very vague under- 

 standing of climatic conditions in Oregon. The question most commonly 

 asked is "What is the average temperature and average rainfall in 

 Oregon?" It is easy to answer this question by giving the normal 

 average temperature for all Observation stations in the State, which 

 is 50.2 degrees, and the average annual rainfall for all the stations 

 which is 38.71 inches. This reply would be worse than valueless to a 

 person intending to settle at Burns where the annual temperature is 

 43.7 degrees, and the annual rainfall is 10.58 inches. The annual 

 temperature also lacks much of being a reliable indicator of summer 

 and winter temperatures. The average annual temperature at Marsh- 

 field, Oregon, is 49.4 degrees; at Heppner, 50.2 degrees, a difference of 

 only .8 of a degree. The temperature of January at Marshfield is 

 44.7 degrees; at Heppner, 32.9 degrees. The temperature of July at 

 Marshfield is 59.4 degrees; at Heppner, 68.8 degrees. The annual 

 temperature at Marshfield is seven degrees warmer than it is at Joseph, 

 but the months of June, July and August are all warmer at Joseph 

 than at Marshfield. 



The person who has always lived in regions where there are but 

 slight differences of elevation above sea level, or which are remote from 

 an ocean, find it hard to understand climatic conditions in Oregon. 

 Except as modified by mountain ranges, the elevation of the State tends 

 to increase towards the south, and we find that the highest annual 

 temperature at any Station is at Blalock on the northern boundary of 

 the State. The ocean profoundly affects the climate by making the 

 winters warmer and the Summers cooler. The remarkably small dif- 

 ference between the temperatures for January and for July at Marsh- 

 field is due to the fact that Marshfield is but a few miles from the 

 ocean. The modifying effect of the ocean is disturbed by ranges of 

 mountains which interfere with and deflect the currents of air from the 

 ocean, as they pass towards the interior. The Coast Range and Cascade 

 Mountains also greatly affect the rainfall in the different portions of 

 the State. The chilling of the air as it rises over the mountains 

 forces out moisture. The loftier the mountains and the lower the 

 temperature reached by the air the less moisture remains in it. It is 

 generally the case that in any given section rainfall increases with 

 altitude, although not necessarily in the same proportion. It is the 



