Island Climate

Photo of man with a very large white balloon.
A weather balloon is released from the St. Paul National Weather Service station (NOAA).

NOAA’s National Weather Service operates a station twenty-four hours a day, every day of the year on St. Paul Island. From 1949 to 2005, the average annual maximum temperature on St. Paul Island was 39º Fahrenheit (F); August was the warmest month with an average maximum temperature of 51.5º F (WRCC 2006; see table below). For the same period, the average annual minimum temperature was 30.9º F; February was the coldest month with an average minimum temperature of 18.8º F. Between 1971 and 2000, the highest average monthly maximum temperature of 55.1º F occurred in August 1993, and the lowest average monthly minimum temperature of 13.6º F occurred in February 1984.

The average total annual precipitation on St. Paul Island from 1949 to 2005 was 23.67 inches (in.), with the most rain (3.10 in.) falling in August on average. The average total annual snowfall was 56.2 in., with snowfall beginning in October and continuing as late as June. The highest average monthly snowfall occurred during December (9.8 in.) and the highest average snow depth occurred in March (7 in.).

This data from the National Weather Service can be compared with early twentieth century accounts of the Pribilof Islands’ weather and climate. Wilfred H. Osgood, et al., (1915, 18) wrote:

The range in temperature is very slight, the thermometer seldom rising above 50º F. in the summer, and in winter ranging usually between 20º and 25º and rarely falling lower than 12º. There is much precipitation, usually falling in the form of drizzly rains or light snows. Chilly fogs are of almost constant occurrence during summer and the winds are at other seasons sometimes very violent.

In the 1920's, G Dallas Hanna offered the following observations:

The winters are exceedingly variable in severity. Ice may form on the freshwater ponds four feet thick and again it may not freeze over ten inches. Great banks of snow 10 or 12 feet deep may pile up and again there may not be enough to track a fox. A midwinter thaw always occurs in January or February and may last from a few days to a month and a half. The temperature never goes low; 12º and 16º [F] below zero are the records for St. George and St. Paul, respectively, and these came but once, during 46 years. Barely does the temperature go to zero for more than a day or two in winter. But the excessively humid atmosphere with the incessant winds makes it very raw and disagreeable out of doors. (Hanna 2008, 245–246)

Summer temperatures on the Pribilofs are very uniform, day and night. Rarely does the thermometer go higher than 55º or lower than 45º. (Hanna 2008, 243)

Beginning about the middle of May, dense fogs almost constantly envelop the islands until in August, to the great consternation of all mariners. In all this time there is rarely a day of sunshine, almost never two in succession. (Hanna, 241)

Sea ice reached St. Paul Island and St. George Island in March 2007 and January–April 2008. It reached St. Paul Island during January and February 2006, April 2005, January and February 2002, March 1999, and April 1997 (Page 2006, pers. comm.; Blizzard 2006, pers. comm.). The writings of Osgood et al. (1915, 18) and Hanna (2008, 246) suggest sea ice (drift ice) was more common in the early twentieth century than today. Osgood et al. (1915, 172) indicated that ice pack “frequently closes in about the shores.” Hanna (2008, 248) stated, “Drift ice usually visits the islands every winter. The time of arrival has been from the first of January to the last of March and it may stay a few days or a few months. Rarely has it been known to remain as late as June 15.” W. H. Dall provided a map of the 1896 winter and summer southern limits of ice pack in the Bering Sea (Dall 1899, 539–546). The effect of sea ice on surface water temperatures during late spring and summer appear in part, related to the occurance and density of fog at the Seal Islands.

St. Paul Island, Alaska Monthly Climate Summary: 9/1/1949 to 9/30/2005

 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Annual

Average Max. Temperature (F)

30.3

27.5

29.2

32.9

39.6

46.0

50.1

51.5

48.9

42.2

37.2

32.7

39.0

Average Min. Temperature (F)

 22.2

18.8

20.0

24.4

31.5

37.5

42.9

44.9

40.7

33.9

29.4

24.3

30.9

Average Total Precipitation (in.)

1.79

1.28

1.17

1.18

1.23

1.26

2.03

3.10

2.85

2.93

2.80

2.06

23.67

Average Total Snowfall (in.)

9.7

9.5

9.7

5.7

1.9

0.1

0.0

0.0

0.0

2.5

7.3

9.8

56.2

Average Snow Depth (in.)

4

6

7

5

1

0

0

0

0

0

1

2

2

Scroll to see entire table.
Source: Western Regional Climate Center (2006).