July weather forecast and climate
St. Louis, MO

July in St. Louis is a hot summer month, with average temperature varying between 89.1°F (31.7°C) and 71.1°F (21.7°C).

Temperature

July is the warmest month in St. Louis, with an average high-temperature of 89.1°F (31.7°C) and an average low-temperature of 71.1°F (21.7°C).

Heat index

The average heat index is evaluated at a sweltering 102°F (38.9°C). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'felt air temperature', 'apparent temperature', or 'feels like', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Additional factors like activity, clothing, pregnancy, and metabolic differences affect individual temperature impact. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. High relative humidity reduces the evaporation rate, resulting in a lower heat removal rate from the body, causing the perception of being overheated. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

In July, the average relative humidity in St. Louis, Missouri, is 68%.

Rainfall

In July, in St. Louis, the rain falls for 8.9 days. Throughout July, 4.11" (104.4mm) of precipitation is accumulated. In St. Louis, during the entire year, the rain falls for 112.6 days and collects up to 40.96" (1040.3mm) of precipitation.

Snowfall

May through October are months without snowfall in St. Louis.

Daylight

In July, the average length of the day in St. Louis is 14.5h.

Sunshine

The month with the most sunshine in St. Louis is July, with an average of 10h of sunshine.

UV index

June through August, with an average maximum UV index of 9, are months with the highest UV index in St. Louis. A UV Index value of 8 to 10 symbolizes a very high health vulnerability from unsafe exposure to the UV radiation for the average person.
Note: The average daily UV index of 9 transform into the following instructions:
Take extra precautions. Fair-skinned individuals may get burned in less than 10 minutes. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise.