July weather forecast
St. Louis, MO

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

Temperature

The warmest month in St. Louis is July, 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

In July, the average heat index is estimated at a very hot 102.2°F (39°C). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Note that heat index values are valued for light wind and location in the shade. 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 'apparent temperature', 'feels like', 'felt air temperature', or 'real feel', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Additional factors like metabolic differences, wind, pregnancy, and activity influence one's weather impression. 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 especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. A higher relative humidity affects normal body cooling by reducing the evaporation rate, subsequently lowering the rate at which the body cools and increasing the perception of heat. 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 is 68%.

Rainfall

In St. Louis, in July, during 8.9 rainfall days, 4.09" (104mm) of precipitation is typically accumulated. Throughout the year, in St. Louis, there are 112.6 rainfall days, and 40.94" (1040mm) of precipitation is accumulated.

Snowfall

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

Daylight

In St. Louis, Missouri, the average length of the day in July is 14h and 33min.
On the first day of July in St. Louis, sunrise is at 5:40 am and sunset at 8:29 pm. On the last day of the month, sunrise is at 6:01 am and sunset at 8:12 pm CDT.

Sunshine

July has the most sunshine of the year in St. Louis, Missouri, 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 estimate of 8 to 10 represents a very high health vulnerability from exposure to the Sun's UV rays for the average person.
Note: The average daily UV index of 9 in July transform into the following instructions:
Take extra precautions. Protection against sun damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. 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.