Cody experiences a semi-arid climate (Köppen BSk). The weather in the Big Horns is highly variable, with large temperature swings always possible. Winters normally bring average lows of 10 °F (-12 °C), and summers can bring record highs of 100 °F (38 °C). Relative humidity is usually a fairly dry 30% or less. Precipitation averages 9 inches (229 mm) of rain per year, making the surrounding area a semi-arid desert. During June, July, and August, if it does snow, it is usually brief and melts quickly. Such events are not frequent, but there are sudden and drastic shifts in weather conditions. Cody enjoys about 300 days of sunshine per year.
Wind is almost a constant presence in the Cody area and the Big Horn Basin in general. Air flow in the Basin is turbulent, but during the winter most storms move in from the north-northwest. During the summer it is not unusual to see storms move in from the southwest. Throughout a normal day, winds can be experienced as coming from almost any direction, mostly from the north and west, but sometimes from the south and east. The Canyon at the west end of Cody funnels rain and wind across the city from the west. The winds can be quite strong at 30 to 40 mph (50 to 60 km/h) and last for several days.
Because of the dry climate, the entire area is laced with irrigation canals, holding ponds, laterals, and drops. The Buffalo Bill Dam between Rattlesnake and Cedar mountains forms a large reservoir about 10 miles (16 km) to the west of Cody. This reservoir (among others) feeds the Shoshone Project, a large irrigation water distribution system
