Continental polar Canadian (cP)

(Continental Arctic cA)

Formed in northern Canada

Move southeastward across Canada in northern US. Winter bring cold weather.

Summer cool, dry weather

Maritime polar Pacific (mP)

Originate over the North Pacific Ocean

Very moist but not extremely cold. Pacific Coast most affected. May bring cool and dry weather to mid-US

Maritime polar Atlantic (mP)

Form over the North Atlantic Ocean

Winter usually bring cold, cloudy weather and precipitation. Summer produce cool weather with low clouds and fog. Move eastward toward Europe.

Continental tropical (cT)

Form over the deserts of northern Mexico and southwestern US

Flow over North America during the summer. Move northeastward, bringing clear, dry, and very hot weather.

Maritime tropical gulf and Maritime tropical Atlantic (mT)

Form over warm waters of the Gulf of Mexico and the tropical North Atlantic Ocean.

Move northward across the eastern US. Winter brings mild, often cloudy weather. Summer brings hot, humid weather, thunderstorms and hurricanes.

Maritime tropical Pacific (mT)

Form over the warm areas of the North Pacific Ocean

Winter may bring heavy precipitation and thunderstorms to the coast and the southwestern deserts.