Below the Arctic-alpine the Hudsonian Life-zone stretches the entire length of the Cascades. Temperatures are low, especially in winter; then the thermometer does not rise above zero for weeks at a time. The average annual temperature at Paradise, 5500 feet, Mt. Rainier, is 38.6° (all temperatures given here are in degrees Fahrenheit). Snowfall is heavy. The average yearly snowfall, for four years, at Mt. Baker Lodge, at 4200 feet elevation, Whatcom County, was 478 inches; at Goat Lake, 2900 feet, Snohomish County, 261 inches; Tye, Stevens Pass, 3010 feet, King County, 398 inches; Paradise, 5500 feet, Mt. Rainier, 587 inches. The deepest snow recorded at Paradise was 27 feet, 2 inches on April 2, 1917. Following the spring thaws the mountain passes are opened to travel, usually in April or May, although nightly temperatures in April and May are still below zero. Spring precipitation is heavy, the monthly average for a twelve-year period at Paradise being 6.78 inches in April and 5.5 inches in May. Summer temperatures are high in the daytime, when the sun beats down through the rarefied atmosphere, but cool at night when accumulated heat is lost through the thin atmospheric blanket. In summer precipitation is light, averaging, at Paradise, 3.46 inches in June, .9 inches in July, and 3.44 inches in August. In the autumn the temperature, both daily and nightly, drops somewhat, and rain and cloudiness are the rule. At Paradise the average precipitation in September is 8.29 inches and in October 10.02 inches. The winter snows usually arrive by the middle of November.
Fig. 8. North side of Mount Rainier, 14,408 feet, with Mount Adams at left and Mount St. Helens at right. June 19, 1932. (Photo by 116th Photo Section, Washington National Guard, No. 011-36A-116.)
Trees that are characteristic of parts of the Hudsonian Life-zone include the alpine fir (Abies lasiocarpa), mountain hemlock (Tsuga mertensiana), Alaska cedar (Chamaecyparis nootkatensis) and white-barked pine (Pinus albicaulis). The following shrubs are listed by Jones (1938) as common in the Hudsonian Life-zone on Mt. Rainier: Salix barclayi, Salix commutata, Juniperus sibirica, Alnus sinuata, Ribes howellii, Lutkea pectinata, Potentilla fruticosa, Sorbus occidentalis, Spiraea densiflora, Pachistima myrsinites, Arctostaphylos nevadensis, Arctostaphylos uva-ursi, Cassiope mertensiana, Cassiope stelleriana, Phyllodoce empetriformis, Rhododendron albiflorum and Gaultheria ovalifolia.
There are extensive coniferous forests in the Canadian Life-zone, still lower on the mountain slopes. This is an area of lesser temperature extremes than is the Hudsonian Life-zone. The average annual temperature at Longmire, 2761 feet, Mt. Rainier, is 43.8°. The average temperature for the winter months, however, is below freezing. In July and August the temperatures are high, especially in the daytime. The eighteen year average for Longmire during these months is 60.6°. Snow is regular but the fall is lighter than in the Hudsonian Life-zone. The annual average, over a period of nineteen years, is 184.4 inches at Longmire. Precipitation is similar to that in the Hudsonian Life-zone, averaging perhaps slightly less.
In the Cascades the typical feature of the Canadian Life-zone is the extensive coniferous forest that extends, almost without a break, the entire length of the Cascades on both sides of the main crest. In addition to Douglas fir, the following trees occur in this forest: western hemlock (Tsuga heterophylla), amabalis fir (Abies amabalis), white pine (Pinus monticola) and noble fir (Abies nobilis). Other plants include Vaccinnium ovalifolium, Vaccinnium membranaceum, Menziesia ferruginea, Alnus sinuata, Acer circinatum, Sorbus cascadensis, Cornus canadensis, Clintonia uniflora, Stenauthium occidentale, Galium oreganum, and Prenanthes lessingii. Saprophytes abundant in, if not confined to, this zone are listed by Jones as: Monotropa uniflora, Monotropa hypopitys, Allotropa virguta, Newberrya congesta, Pterospora andromedea, Corallorrhiza maculata, Corallorrhiza mertensiana and Corallorrhiza striata.
West of the Canadian Life-zone in the western Cascades, the coniferous forests merge with the lowland forests of western Washington. To the east of the Canadian Life-zone in the eastern Cascades, there is a distinct change to a more arid climate and flora. At Leavenworth, 1167 feet, Chelan County, the annual average precipitation is but 19.5 inches and at Cle Elum, 1930 feet, but 23.23 inches. Temperatures are higher, the annual average of the above two localities being 47.2° and 45.4° respectively. The winter months are cold, with the average temperature in January and February below freezing. In summer the averages in July and August at Leavenworth are 68.8° and 68.0°, with the average maximum being 87.5° and 86.1°. Snowfall is heavy, the yearly average at Leavenworth being 98.5 inches and at Cle Elum 86.3 inches. The effect of this more arid climate is seen in the vegetation. The dense Douglas fir forest, is replaced by more open forests of yellow pine (Pinus ponderosus). Groves of oak (Quercus garryana) are found near streams. The open forests give way to the extensive grasslands bordering the desert. The transition of vegetation is similar to that occurring in the Yakima Valley Area.