George H. Taylor, the state climatologist with the Oregon Climate Service, provides detailed statistical information concerning Oregon weather patterns. Here are a few facts on which to gauge what kind of whether you may face.
• July is consistently the driest month throughout Oregon.
• Western Oregon receives the bulk of its annual precipitation during winter. In fact, there's measurable precipitation more than half the winter days. In summer, only 10 to 15% of the days are wet.
• Although there is some variation from north to south, the wettest months tend to be the November-March period.
• Although rain can occur during the warm season, average totals during those months are generally lower than during winter.
• East of the Cascade Mountains, the monthly rainfall averages are much more uniform. Some locations receive more rain in summer than in winter.
• Precipitation is highest near the coast and in higher elevations, and increasingly lower as you move eastward.