Climate and Rainfall
The local climate is humid with a strong marine influence and moderate year-round temperatures. Average annual rainfall ranges from a low of 45 inches in the Camas Valley area to approximately 120 inches in the headwaters of the South Fork. Seventy-five percent of annual precipitation occurs between the months of November and March, often in heavy storm events. Rainfall is quite variable and appears to be a function of cyclical patterns occurring on 20-to 30-year intervals.
Due to the typically southern winter storm track and the orientation of the ridges in the drainage, the East Fork and South Fork of the Coquille receive the most rainfall. Between 75 and 120 inches fall annually east of China Creek in the East Fork and above Powers and including Dement, Rowland, and Baker Creeks in the South Fork. The headwater of Myrtle and Rock Creeks in the Middle Fork drainage and the headwaters of Middle and Cherry Creeks in the North Fork also receive between 75 and 120 inches of rain annually. The rest of the basin receives between 50 and 75 inches per year with the exception of the Camas Valley area which receives someshat less than 50.