University of Michigan 



limits of temperature range are from -76° to 100° F., a range of 



176°, and yearly ranges of over 150° are normal. The daily range 



also is often great, especially in summer, and killing frosts may 



occur in any month of the year. 



To indicate the climatic conditions during the various seasons, 



the monthly averages of temperature and precipitation are given 



for Tanana (Table II). A noticeable feature is the scanty amount 



of precipitation. 



TABLE II 



Tanana, Monthly Averages 



At Tanana in 191 1 the leaves on the birches and poplars began 

 to turn yellow in late August, and by late September nearly all the 

 leaves had fallen. A light snow fell in the Yukon Valley on 

 October 2, and the surface of the ground had frozen solid by 

 October 20. Ice began to run in the Yukon on October 25, and 

 the river froze over on November 8, at a temperature of about 

 -14° F. Numerous light snows fell during October and November, 

 but the snow did not become deep enough to require snowshoes 

 until the middle of December. However, the snow was said to 

 have come late that year. 



In the spring of 191 2, at the head of the north fork of the 

 Kuskokwim, a thawing temperature was first reached on March 22, 

 though the snow had by that time partly melted off the exposed 

 slopes. The snow melted slowly, but was almost entirely gone by 

 April 26; the ground, however, remained frozen for several weeks 



