III. CLIMATE (Historic Alaska Information)
The impression is general that the climate of Alaska is arctic in its character and its severity. Several years since life insurance was refused a resident of Ketchikan on the ground that undue risks were entailed by his harsh surroundings and especially severe climate. It is difficult to convince people that there is no typical Alaskan climate, any more than there is an European or American climate. The extremes of latitude and longitude in Alaska find their parallel in Europe between Norway and Sicily equal to the difference between Point Barrow and Ketchikan and from western France to central Russia, about the distance from the Alaskan Peninsula to Skagway.
Attempts to convey an idea of climate by the annual means of temperature, rainfall, etc., are fallacious and unsatisfactory. The temperature equability is best shown by the mean temperatures of the warmest and of the coldest month. As an illustration it is known that San Francisco and St. Louis, which are in substantially the same latitude, have the same mean annual temperature, about 55:7°. The variations of the former place are small and inconsiderable, from 50.2° in January, the coldest month, to 59.7° in September, the warmest month a range of less than 10° in the monthly means. In St. Louis, however, the range is from 31.6° in January to 78.4° in July a range of 46.8°, or nearly five times as great as at San Francisco. It is pertinent to note that the coldest month of Sitka, 31.4°, closely agrees with the coldest month of St. Louis.
As a matter of fact the mean monthly temperatures of Alaskan stations are very high, when one takes into consideration the northern latitudes of the territory. Naturally the Aleutian Isles are favored by most equable temperatures through the influences of the Pacific Ocean. This is shown by the mean temperatures of Unalaska of 51° for August and 30° for February. Unalaska, it may be noted, is in 54° N., the latitude of southern Labrador.
While the modifying oceanic influences affect the southern Alaskan coast to the very peninsula, it is most noticeable in Sitkan Alaska, which presents a northerly extension of the temperature conditions of the California and Washington coast region, especially during the summer. The mean temperature of San Francisco, Cal., and Port Angeles, Wash., for August is 58°, while that of Sitka is 57°, and of Juneau for July 57°.
In general the Sitkan archipelago presents a humid, equable climate, with cool summers, warm winters, and very frequent rain or snow. Of the coast stations Sitka is typical, with its annual rainfall of 111 inches, its mean of 33° for the coldest month, February (practically identical with the January mean of St. Louis), and of 57.2° for the warmest month, August.
Along the coast extremes are rarely known, the highest in 45 years at Sitka being 87° in August, while the lowest ever recorded is 3° in February. Compare these figures with St. Louis, 106° in August and 21.5° in January, and the equability of temperature in southeastern Alaska is obvious. Similar temperature conditions obtain in summer from the St. Elias region westward to the Alaskan Peninsula, though the winters are considerably colder. Along this coast the precipitation rain in the south and snow in the north is frequent and heavy, being sometimes excessive. For instance, at Valdez the snowfall in the winter of 1902 1903 was 60 feet 11 inches, the maximum snowfall here observed; the average annual precipitation is 72.8 inches of rain and melted snow. At Nuchek Harbor, near by, there was a rainfall in one year of 190 inches. These large amounts of rain and melted snow indicate that over the adjacent regions there fall in some years from 60 to 150 feet of snow, which explains clearly the presence of the proportionately large number of living glaciers in Prince William Sound and It akutat Bay.
In this connection Professor George Davidson points out the great desirability of regular climatological observations, especially with reference to sea-currents, winds, humidity, and rainfall.
Farther to the northward the coasts are washed by the Bering Sea, a cold body of water with an average temperature of about 39°. In consequence of the cold sea, its adverse winds, and the increasing northing it is natural to find a harsher climate from Bristol Bay northward. The conditions of the southern half of Seward Peninsula, of which Nome is the business centre, are best indicated by the records of St. Michael, 100 miles south of Nome, where the equable and high summer temperatures (53.6° in July) are offset by low winter means reaching 2.3° in February. Its rain and melted snow during the year averages 14.6 inches.
The Arctic coasts from their high latitude, and consequent loss of the midwinter sun, forty days at Point Barrow, experience prolonged winter cold and brief summers. The scanty precipitation is almost entirely in the form of light, winter snowfalls. Point Barrow is a typical winter station, with a yearly rainfall of 6.62 inches and average temperatures of 39° in July, the warmest month, and of 21° in January, the coldest month. The severity and length of the winter are shown by the fact that-the average temperature is below zero from November to April, the mean for the six months being thirteen degrees below zero.
As one enters the interior of Alaska, whether by the Copper River, the Kuskokwim, or the Yukon, the climate becomes continental, with great ranges of temperature between the short, comparatively hot summers and long, cold winters. Within a hundred miles of the coast the oceanic influence largely disappears, its gloomy humid aspects giving way to brighter skies and decreasing rain or snow. The culmination of the summer heat and of the winter cold is found at almost the greatest distance from the surrounding seas in the valley of the upper Yukon. The typical station for this region is Fort Yukon with its July mean of 64° and a January mean of 31°, which, compared with Point Barrow, 300 miles to the north, shows a lower temperature of ten degrees in winter and a higher temperature of twenty-five degrees in summer.
The rigors of the past climate are strikingly illustrated by the great depths to which the ground is frozen. In the Nome region a shaft has been sunk 120 feet without reaching ground free from frost, and near Dawson the earth was found frozen to the depth of 200 feet.
See table for the mean temperatures and rainfall for ten typical and well-distributed stations.