The Oregon Coast is at its warmest and driest in summer, where temperatures can reach up to the high 80°s. The winters on the coast are also somewhat mild (depending on your definition) at around 40°.
Direct flights into Portland International Airport (PDX) are the easiest way to reach the northern Oregon Coast. You can also fly into smaller local airports Tillamook Airport (OTK) and Eugene Airport (EUG) for the central coast. We highly recommend renting a car so you can drive along the coast on the US-101 and see the sights.