The climate of the United States varies greatly, due to large differences in latitude, and a wide range of geographic features, including mountains and deserts. West of the 100th meridian, much of the US is semi-arid to arid, including desert in the far southwestern US. East of the 100th meridian, the climate is humid continental in the northern areas (locations above 40° north latitude), to humid temperate from the central Plains east to the middle Atlantic coast regions, to humid subtropical in the Gulf and south Atlantic regions. The southern tip of Florida is tropical.