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Owing to its vast size and varied landforms，the United States has a wide variety of climates ranging from tropical in Hawaii to Arctic in Alaska.The climate of the continental United States also varies greatly.

The west coast enjoys an oceanic type of climate in the north and a Mediterranean climate in the south，and the temperature difference between winter and summer is not very great.The region receives plenty of rain due to storms coming from the ocean，with most of the west coast recording an annual rainfall of over 150 centimeters.The abundance of rain allows plants and trees to grow easily，and large areas of the region are covered by national forests.The abundant rainfall also makes agricultural production profitable in the three great valleys（Willamette，Central and Imperial）that lie inland from the coast.

The situation is very different east of the Cascades and the Sierras.Both ranges block the wet weather systems from the Pacific Ocean，which makes the Great Basin to the east very dry.Most of this area receives annual rainfall of only about 50 centimeters，and some areas only get 12.7 centimeters.As a result，large parts of the Great Basin are desert.The southern part of this region is also very warm.

The Great Plains have a semiarid climate，also known as a continental steppe climate.Here rainfall is scarce and unpredictable.The temperature varies greatly during the year;it is often very hot in the summer and very cold in the winter.

To the east of the Great Plains，the climate is more humid and average annual rainfall increases to about 100 centimeters.In the northeastern part of the continent，the four seasons are distinct;the summers are warm and humid，and the winters long and cold.The southeastern region has a subtropical climate with long hot summers and mild winters.