Climate, which consists of observations of meteorological parameters (i.e., weather) over a specified period of time, is shaped by many environmental factors. Although weather conditions at any particular time can be ephemeral and deviate from expectations, over a long period of time, certain characteristics are associated with any given location on Earth. The longer the period of record, the more likely that climate regimes will be identifiable with recognizable temperature and precipitation characteristics. This entry discusses seasonal changes in climate as well as major controls and localized controls on weather and climate.