Like Western Europe, the Atlantic coast of North America benefits from the warmth of the Gulf Stream. The American southeast has hot and humid summers and warm winters. South Florida records temperatures above 80 degrees F (27 degrees C) even in winter. The temperature never falls below freezing in Key West, Florida. Key West, Galveston, and San Antonio, Texas, and Vicksburg, Mississippi average more than 80 degrees F (27 degrees C) in July. The Gulf Stream brings rain to the American southeast. The Gulf Coast between New Orleans, Louisiana and Mobile, Alabama averages more than 60 in. (162 cm.) of rain per year.
At the other end of North America, the California Current cools the Pacific Coast. San Diego averages 67 degrees F (19 degrees C) in July, whereas Savannah, Georgia, at comparable latitude, averages 80 (27 degrees C) in July. The Pacific coast receives the most rain in North America. Wynoochee Oxbow, Washington averages 146 in. (371 cm.) of rain per year. Away from the moist Pacific air, the interior of North America receives less rain. The Colorado basin averages fewer than 3 in. (8 cm.) of rain per year. The Great Plains are prone to drought, with disastrous results in the 1870s and 1930s.
The Pacific Ocean warms British Columbia, Canada. Victoria and Vancouver, British Columbia average 39 degrees F (4 degrees C) in January. Away from the warmth of the Pacific and the Gulf Stream, northern latitudes are cold. The coldest winters occur between the Hudson Bay and Alaska. Fort Good Hope, near the Arctic Circle, has recorded minus 79 degrees F (minus
62 degrees C). Fort Vermillon, Canada has recorded minus 78 (minus 61 degrees C) and Churchill, Manitoba minus 57 (minus 49 degrees C) in January.
Storing the heat from the summer sun, the Great Lakes warm adjoining lands year round. The effect of the Great Lakes is mild, but measurable in winter. Toledo, Ohio, near Lake Erie, has recorded minus 16 degrees F (minus 9 degrees C) , whereas Columbus, Ohio, 100 mi. (161 km.) south and thus outside the moderating effect of Lake Erie, has recorded minus 20. Snowfall is heavy in the Great Lakes; clouds absorb moisture from the lakes, returning it to the region as snow. As in the Mediterranean, autumn is warmer than spring in North America. In autumn, temperatures reminiscent of summer often follow a cold spell. Americans know this time as Indian summer.
South of the United States stretch Mexico, Central America, South America, and the Caribbean islands. Moving south through Mexico, rainfall increases. The warmth of the Pacific Ocean makes the western coast of Mexico among the hottest lands in the Americas. The coasts of Central America are hot and rainy. The mountains of the interior are comparatively cool, though rainfall is abundant. Most of Central America receives more than 100 in. (254 cm.) of rain per year. Warmed by tropical waters on both coasts, Central America displays a uniform temperature. Panama averages roughly 80 degrees F (27 degrees C) year round.
South America narrows moving south. The decreasing width of the continent amplifies the effect of ocean currents on the southernmost lands. The east coast of South America, warmed by the Atlantic Ocean, is 10
degrees F (6 degrees C) warmer than the western coast at comparable latitudes. Tropical South America is cooler than tropical Africa because the former has thicker clouds, heavier rains, and denser forests than the latter. As far south as the Tropic of Capricorn, South America averages more than 70 degrees F (21 degrees C) year round. South America is warmer in winter and cooler in summer than comparable latitudes in North America.
The heaviest rains fall east of the Andes Mountains, summer being the rainy season. Moist equatorial air, flows east to west across South America. The Amazon River valley receives more than 80 in. (203 cm.) of rain per year, with some locales tallying 100 in (254 cm.). The continent receives rain at least 250 days per year.
The Caribbean Sea and the Gulf of Mexico, with temperatures above 80 degrees F (27 degrees C) year round, warm the Caribbean islands. The climate is hot and humid. Rain is heaviest in June and again in October, with less rain falling in July and August. Moore Town, Jamaica averages 222 in. (564 cm.) of rain per year, and Port Antonio, Jamaica averages 137 in. (348 cm.). Kingston, Jamaica, on the leeward side of the mountains, averages only 31 in. (79 cm.) of rain per year. The moderating effect of the Caribbean Sea and the Gulf of Mexico holds temperatures constant. Only four degrees separate January and July mean temperatures in Barbados. The Caribbean, Florida, and the Gulf Coast are vulnerable to hurricanes.
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