30 CONTRIBUTIONS FROM ‘THE NATIONAL HERBARIUM. 
If the records are considered separately for the stations located 
within the line of 10 inches of rainfall the average number. of clear 
days for these same years is 166, 168, and 193. 
These data show very clearly that eastern Washington has much 
more sunshine than western Washington, and also that in the region 
of less than 10 inches rainfall, which closely coincides with the 
Upper Sonoran area, the amount of sunshine is considerably greater 
than for the average of eastern Washington. 
The following percentages are based on the normal sunshine map 
of the United States Weather Bureau: The least amount of sunshine 
is in the very humid region, which has over 90 inches of annual rain- 
fall. Less than 40 per cent of the days here are clear, a low percent- 
age equaled in the United States only on the upper peninsula of 
Michigan, in northern New York, and in northern New England. 
In the region of less than 10 inches rainfall over one-half of the 
days of the year are clear, thus corresponding in general with the 
broad basins of the Missouri and Mississippi valleys and with the 
Southern States. The remainder of the State has from 40 to 50 per 
cent of the days clear, resembling in this respect the region of the 
Ohio Valley northward and eastward. 
TEMPERATURE. 
WESTERN WASHINGTON. 
' Temperature records of the United States Weather Bureau are 
available for over 30 stations in western Washington, all located 
in the Humid Transition area, for periods varying from one year to 
thirty years. The normal annual mean temperature based on these 
records is 49.3° F. The same average for each of the 30 stations 
shows the lowest to be Port Crescent, 46.6°, and the highest to be 
Vancouver, 52°. The normal monthly mean temperatures of the 
same stations vary as follows: 
Temperature data for Humid Transition area. 
Month. Degrees F. | Month. Degrees F. 
January _...-...---.------ 85 to 40 | July -...-..-2--2 56 to 66 
February. _...------------ 37 to 43 | August _-._..---.-__-___- 56 to 66 
March..... _----.---.--.. 38 to 46 | September -_..__.._____-- 53 to 60 
April. _....----.---------- 45 to 51 | October _._._.-___._____-- 47 to 58 
May ...._-..-.------ ~~... 50 to 58 November. _.__.---------- 38 to 46 
June ____. ---_ eee 54 to 62 December ______________- 34 to 43 
rf 
The highest temperature ever recorded at any of these stations is 
100°; the lowest is — 2°. 
