Missouri has a continental climate, but with considerable local and regional variation. The average annual temperature is 50°F (10°C) in the northwest, but about 60°F (16°C) in the southeast. Kansas City has a normal daily mean temperature of 54°F (12°C), ranging from 26°F (–3°C) in January to 79°F (26°C) in July; St. Louis has an annual mean of 56°F (13°C) with 29°F (–2°C) in January and 80°F (27°C) in July.

The coldest temperature ever recorded in Missouri was –40°F (–40°C), set at Warsaw on 13 February 1905; the hottest, 118°F (48°C), at Warsaw and Union on 14 July 1954. A 1980 heat wave caused 311 heat-related deaths in Missouri, the highest toll in the country; most were elderly residents of St. Louis and Kansas City. Fifty-one more heat-related deaths occurred in St. Louis during a 1983 heat wave.

The average annual precipitation for Kansas City (1971–2000) was 40 in (100 cm), with some rain or snow falling about 110 days a year. The heaviest precipitation is in the southeast, averaging 48 in (122 cm); the northwest usually receives 35 in (89 cm) yearly. Snowfall averages 20 in (51 cm) in the north, 10 in (25 cm) in the southeast. During the winter, northwest winds prevail; the air movement is largely from the south and southeast during the rest of the year. Springtime is the peak tornado season.