St. Louis (MO) Temperature by Month

St. Louis in Missouri, United States of America sees significant seasonal temperature differences, with daytime highs between 5°C (41°F) in January and 32°C (90°F) in July, averaging 19°C (66°F) annually. Explore the full monthly breakdown below.

Visitors to St. Louis can expect significant temperature changes throughout the year. Nighttime temperatures also vary widely, ranging from 21°C (70°F) in July to -5°C (23°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in St. Louis by month:

The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM. July, the city's warmest month, gets 311 hours of sunshine.

The chart below shows the average temperature throughout the year:

St. Louis's average annual maximum temperature is 19°C (66°F). To put that in context, here's how it compares to a few well-known destinations:

Seville, Spain averages 23°C (73°F) a year, one of the warmer cities in Western Europe, with long hot summers.

Reykjavík, Iceland averages 9°C (48°F) a year, mild summers by Icelandic standards, but cold winters and frequent wind.

Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.

Melbourne, Australia averages 20°C (68°F) annually, known for unpredictable weather, with four seasons sometimes happening in one day.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.

In St. Louis, January is the coolest month, with average highs of 5°C (41°F) and humidity around 72%, considered high. In July, the warmest month, temperatures average 32°C (90°F) with 68% humidity, conditions that feel high. For a full picture, see our humidity page.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained, so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.

For more on St. Louis's weather, including monthly rainfall, sunshine hours, and humidity, visit our St. Louis climate page.