Washington's topography, together with warm sea currents, strongly affects the climate, which varies greatly in different areas. Rainfall ranges from extremes of 6 inches in the eastern part to 160 inches in the western. East of the Cascades summer temperatures are often above 100° F. Not uncommonly, eastern Washington winters drop to -- 20° F. and -- 300° F., and crop seasons in the northern and higher portions are sometimes less than 100 days, increasing to 200 days towards the south. The average annual precipitation of 16 ½ inches in this section ranges from 60 inches in the mountains to 6 inches on the plains. The westerly prevailing wind's average velocity is low -- between 5 and 6 miles per hour -- but occasional sand or dust storms visit the and areas.
In western Washington, the heaviest rainfall in the United States occurs on the southwestern slope of the Olympics, at Wynooche, where the average is 141 inches. On the northern side of the Olympics, Sequim has the lightest rainfall, averaging 17 inches, and requires irrigation. The average in the western section, however, is 36 inches. The rainiest month is likely to be December, and the driest, July. Winter temperatures average 40° F., with a daily average minimum of 35°. Summers average 61° F. with a daily average maximum 0f 74°. Yearly snowfall varies widely, averaging less than 13 inches at Seattle, while Snoqualmie Pass has had 400.
Puget Sound area crop seasons average 207 days, diminishing to 185 in the valleys south. First frosts usually occur in November, and the last frosts in March. Wind velocities vary from a yearly average of greater than 12 ½ miles on the coast, with occasional seasonal bursts of hurricane intensity, to 6 miles per hour in the interior.
Washington is a region where nature, on the whole, has been kind, barring it from catastrophic earthquakes, cyclones, drouths, and extensive floods, and endowing it with a climate assumed by scientists to be highly favorable for physical and mental exertion.