KOPPEN-GEIGER CLIMATE CLASSIFICATION SYSTEM FOR CANNON BEACH :

 
Cfb: MARINE WEST COAST - MILD

-AVERAGE TEMPERATURE OF ALL MONTHS IS BELOW 71.6°F
-AT LEAST 4 MONTHS WITH AN AVERAGE TEMPERATURE ABOVE 50°F
-AVERAGE TEMPERATURE OF COLDEST MONTH IS UNDER 64.4°F AND ABOVE 26.6°F
-RAINFALL EQUALLY SPREAD THROUGHOUT YEAR

Cfc: MARINE WEST COAST - COOL

-AVERAGE TEMPERATURE OF ALL MONTHS IS BELOW 71.6°F
-1 TO 3 MONTHS WITH AN AVERAGE TEMPERATURE ABOVE 50°F
-AVERAGE TEMPERATURE OF COLDEST MONTH IS UNDER 64.4°F AND ABOVE 26.6°F
-RAINFALL EQUALLY SPREAD THROUGHOUT YEAR

CONTROLLING FACTORS – APPLIES TO BOTH Cfb & Cfc:

-WEST COAST LOCATION (YEAR ROUND INFLUENCE OF THE WESTERLIES)
-WARM OCEAN CURRENTS ALONG MOST OF THE COASTS
-LOCATIONS: COASTAL OREGON, WASHINGTON, BRITISH COLUMBIA, SOUTHERN ALASKA
                         NORTHWEST EUROPE, SOUTHERN CHILE, INTERIOR SOUTH AFRICA
                        SOUTHEAST AUSTRALIA, NEW ZEALAND
-DISTINGUISHING CHARACTERISTICS: MILD WINTERS AND MILD SUMMERS WITH LOW ANNUAL TEMPERATURE RANGE, HEAVY CLOUD COVER, HIGH HUMIDITY, FREQUENT CYCLONIC STORMS WITH PROLONGED RAIN, DRIZZLE OR FOG, 3 TO 4 MONTH FROST PERIOD DURING THE WINTER SEASON


Source: http://www.utexas.edu/depts/grg/kimmel/GRG301K/grg301kkoppen.html