Coos County lies along the southern part of the Oregon Coast. It is wholly within Climate Division 1 (Oregon Coast) established by the National Climatic Data Center. Below is a description of the climate of Division 1 followed by specific descriptions of Coos County. Climate tables for various parameters, as observed at long-term climate stations in Coos County, are included below.
Climate Division 1 — Oregon Coast
Stretching along Oregon's Pacific border, the coastal zone is characterized by wet winters, relatively dry summers, and mild temperatures throughout the year. Coastal terrain features include a coastal plain (extending from less than a mile to a few tens of miles in width), numerous coastal valleys, and the Coast Range, whose peaks range from 2,000 to 5,500 feet above sea level and extend down the full length of the state. Rivers such as the Coquille, Umpqua, and Yaquina dissect the Coast Range and drain its slopes. The area's heavy precipitation results from moist air masses moving off the Pacific Ocean onto land, especially during winter months. The abundant moisture supports lush pastures for dairy and animal production as well as valley crops of grass seed, flower bulbs, nuts, and fruit.
Along the lower elevations of the immediate coast, normal annual precipitation is between 65 to 90 inches. However, spots high on the west slopes of the range may get up to 200 inches. Several days of abundant rainfall can cause strong flood events. In some locations, flood control dams have greatly reduced the incidence of damaging floods. As is typical of western Oregon, the highest monthly precipitation values for the coast occur in the winter months of November, December, and January. Table 1 is a summary of mean monthly and annual precipitation for recording stations in the coastal zone. Figure 1 shows NOAA climate stations in Zone 1, which were in operation during the 1961-1990 period. Figure 2 shows the Coos County region from the Oregon annual precipitation map. Table 2 lists the average number of days with precipitation amounts exceeding certain thresholds.
Snowfall' in tcoastal vicinity is minimal, usually only one to three inches. Some of the higher elevations receive significant amounts of snowfall, however. For example, in January of 1982, Laurel Mountain (elevation 3,589') received 55 inches of snow. At Mary's Peak (elevation 4,097'), the highest peak in the Coast Range, snow often lasts into May. Table 4 lists average monthly and annual snowfall totals for various stations.
The months of July, August, and September tend to be the warmest, but average summer temperatures are only about 15 degrees above the coldest month, January.
Table 3 lists normal monthly temperature at stations in the area. Average heating and cooling degree days (base 65 deg F) are lower for the coastal region than any other Oregon region as a result of the mild temperatures.
Extremely high or low temperatures are rare, and the annual temperature range is lower than any other Oregon climate zone. Temperatures of 90 deg F or above occur, on the average, less than once per year, and freezing temperatures are infrequent. Newport, for example, records temperatures of 32 deg F or below an average of 30 times per year. Killing frosts are even less frequent. Most of the area averages more than 300 days between the last occurrence (in spring) and the first occurrence (in fall) of 28 deg F temperatures. Table 5 and 6 list median frost dates and mean growing seasons, respectively, for four different temperature thresholds.
Occasional strong winds strike the Oregon Coast, usually in advance of winter storms. Wind speeds can exceed hurricane force, and in rare cases have caused significant damage to structures or vegetation. Damage is most likely at exposed coastal locations, but it may extend into inland valleys as well. Such events are typically short-lived, lasting less than one day.
Skies are likely to be cloudy during winter, and only partly cloudy during summer. At Astoria, average winter cloud cover is over 80 percent, dropping only to about 65 percent in summer. Summer cloud cover is due mostly to fog and low clouds. As a result of the persistent cloudiness, total solar radiation is lower here than in any other part of the state.
Established: Dec. 22, 1853
Coos County was created by the Territorial Legislature from parts of Umpqua and Jackson Counties in 1853 and included Curry County until 1855. The county seat was Empire City until 1896, when it was moved to Coquille. Although trappers had been in the area a quarter-century earlier, the first permanent settlement in present Coos County was at Empire City, now part of Coos Bay, by members of the Coos Bay Company in 1853. The name "Coos" derives from a native Coos Bay Indian tribe and translates to "lake" or "place of pines." Forest products, tourism, fishing and agriculture dominate the Coos County economy. Boating, dairy farming, myrtlewood manufacturing, shipbuilding and repair and agriculture specialty products including cranberries, also play an important role. The International Port of Coos Bay, considered the best natural harbor between Puget Sound and San Francisco, is the world's largest forest products shipping port.
(County information obtained from Oregon Blue Book)
Climate Tables (Coos County, Oregon)