The United States has a highly diverse climate because of its large size and wide range of latitude, elevation, and coastal influences. The country includes humid subtropical, humid continental, Mediterranean, oceanic, semi-arid, arid, and alpine climates, so summer and winter conditions vary sharply by region. Coastal and high-elevation areas are often milder, while interior plains, the South, and desert Southwest can be much hotter in summer. Winters range from mild along the Gulf and Pacific coasts to very cold in the northern interior and mountain states. This diversity gives residents and expats many climate choices, but it also means local climate matters far more than national averages.