St. Louis County Climate
St. Louis County, Missouri
Avg Annual Temp
56.6°F
Annual Precip
42.1"
Annual Snowfall
11.6"
Extreme Heat Days
44.099999999999994
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About St. Louis County Weather
Warm Temperate Suburban Corridor
St. Louis County averages 56.6°F annually, placing it firmly above the national median temperature. It experiences a humid continental climate with significant seasonal variability.
Warmer than the State Average
The county’s 56.6°F average temperature is nearly two degrees warmer than the Missouri average of 54.9°F. However, its 42.1 inches of precipitation is slightly lower than the state benchmark.
A Buffer Between City and Country
With 44 days of extreme heat, the county is slightly cooler than the city core but warmer than outlying rural areas. It maintains a July average of 79.4°F, typical for the region.
Predictable Snow and High Heat
The county sees 11.6 inches of snow annually, paired with a January average of 31.5°F. Summers are long and humid, featuring temperatures that stay high well into the evening.
Balance Winter Salt and Summer Air
Residents should prepare for roughly a foot of snow while prioritizing air conditioning for the 44 extreme heat days. Proper insulation helps manage the wide swing between January and July.
Frequently Asked Questions
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.