July weather forecast and climate
St. Louis, MO

July in St. Louis is a tropical summer month, with temperature in the range of an average low of 71.1°F (21.7°C) and an average high of 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 evaluated at a torrid 102°F (38.9°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With the 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 'feels like', 'real feel', 'felt air temperature', or 'apparent temperature', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (wind, clothing, pregnancy). Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. 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. Under high air temperature and humidity (high heat index) conditions, perspiration is limited, and the perception of heat is increased. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

In St. Louis, the average relative humidity 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. Throughout the year, in St. Louis, there are 112.6 rainfall days, and 40.96" (1040.3mm) of precipitation is accumulated.

Snowfall

In St. Louis snow does not fall in May through October.

Daylight

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

Sunshine

With an average of 10h of sunshine, July has the most sunshine of the year in St. Louis.

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 of 8 to 10 symbolizes a very high threat to health from the exposure to the Sun's UV radiation for average individuals.
Note: The daily maximum UV index of 9 interpret into the following advice:
Take special precautions, as unprotected eyes and skin can be burned and damaged quickly. 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. 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. A broad-spectrum sunscreen of SPF 30+ should be liberally applied and re-applied every two hours, and immediately after an outdoor workout or a swim.