|Information courtesy of the
National Climate Data Center
|McGrath is located in western interior Alaska near the western end of a relatively flat drainage basin in the upper portion of the Kuskokwim River valley. The Kuskokwim Mountains extend in a northeast-southwest direction through the McGrath area, but the most pronounced ridges of this range lie to the west of the station. Consequently, the area is, for practical purposes, a portion of the sheltered continental interior. The characteristic continental climate is more pronounced during the winter season when temperatures become quite cold and precipitation relatively light, with pronounced north or northwesterly winds prevailing. During the summer months, when prevailing winds become southerly, the climate is at least partly affected by maritime influences, and the transition periods between the seasons are relatively short. Average summertime precipitation is more abundant than that received by most stations farther inland, but this may be due as much to topographic influences as to maritime influences. High temperatures in the summer reflect the continental influences of the interior, and high temperatures in the fall are just a little below the values reached in other areas farther inland like Fairbanks.
Over 40 percent of the normal precipitation falls during July, August, and September. The winter months have relatively little precipitation in comparison. However, due to the general nature of the dry snow, the accumulated snowfall is usually quite large. Spring is the driest season of the year with considerable clear and mild weather, and this period usually lasts well into June. Most thunderstorms occur during the months of June and July. Small hail occurs several times a year. Break-up of the Kuskokwim River usually occurs in the middle of May and the ground is normally thawed enough for cultivation by the first of June. The normal growing season is approximately 120 days and the average occurrence of the last temperature of 32 degrees in the spring is late May. The first temperature of 32 degrees in the autumn normally occurs in the middle of September.
The summer months are relatively warm for Alaska. On approximately 15 days during the summer the daily maximum rises to the 80s. Relatively high temperatures have been observed during the winter months resulting from influxes of warm maritime air from the ocean. These thaws, usually of one or two days duration, occur several times during the winter season.
During the winter months the minimum temperatures fall to well below zero, at times reaching at least -50 degrees. Long periods of five to ten or more days of extremely low temperatures occur during the winter months. Skies remain clear and atmospheric pressures quite high. In the coldest of these periods high inversion ice-fog and ice.