It's all about the layers here, as there's no other way to keep up with the weather, which can morph from cold and overcast to warm and sunny and back again in the course of a few hours, especially in spring and early fall. Summer days are warm and more consistent, but evenings can cool off substantially. August and September are the glorious, warm, clear months that remind Oregonians why they live there. Bring an umbrella or raincoat for unpredictable fall and winter weather. Hikers will want to bring rain gear and a hat with them, even if they're visiting in summer; insect repellent is also a good idea if you'll be hiking along mountain trails or beaches.