294 TRANSACTIONS OF THE CANADIAN INSTITUTE. ‘(Vou VIII. 
record when the temperature did not reach 60°, and 70° is reached on 
the average twenty days in the month; 80° is reached on six days and 
there are a few instances of 90°. 
The August mean temperature is 54.5°. The month opens warm 
but a very decided downward trend of the temperature curve occurs 
after about the 15th, and there seems to be a decided danger of frost 
after the 20th. It is still quite the early autumn when the temperature 
of Dawson drops below that of White Horse and the southern Yukon 
generally, and the difference as has been shown becomes more and 
more pronounced until after midwinter. With a mean temperature of 
41.6° in September and an average daily minimum little above 
freezing, autumn is soon well advanced in Dawson and the temperature 
sometimes falls below 10° before the month closes. 
October is winter with a mean temperature of 24.1° and zero read- 
ings well before its close. Towards the end of this month ice begins 
to run in the Yukon, but it is not until about ten days later that the 
river sets fast. 
November mean is —1°; the temperature very seldom rises to the 
freezing point; on twenty days it falls below zero and on seven to— 
— 20° or lower with an occasional dip to — 40°. 
The December average mean temperature at Dawson is — 10°; the 
highest mean in ten years was. zero and the lowest —18°; readings 
below —40° are usually recorded on about three days each December 
and —50° may be reached; there are few days on which zero is not 
recorded. The White Horse average temperature is nearly 20° higher 
than at Dawson. 
Short as has been the temperature record at Dawson, that of 
precipitation has been shorter, covering a period of but five years at 
Dawson and much less at other stations. 5 
As an approximation however, the annual snowfall in the Yukon 
is about 52” and the rainfall 7.5” July, August and September are the 
months of largest rainfall, each averaging a fall of something under 
two inches, much of which comes with thunder storms. Most of the 
snow falls late in the autumn but occasional light. falls occur up to 
April or even May. 
