August weather forecast
St. Louis, MO

August, the last month of the summer in St. Louis, is another tropical month, with an average temperature ranging between max 88°F (31.1°C) and min 69.4°F (20.8°C).

Temperature

In August, the average high-temperature in St. Louis, Missouri, is relatively the same as in July - a still tropical 88°F (31.1°C). In St. Louis, the average low-temperature is 69.4°F (20.8°C).

Heat index

The average heat index in August is estimated at a torrid 100.4°F (38°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 'felt air temperature', 'feels like', 'apparent temperature', or 'real feel', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. This effect is individual, with diverse people perceiving weather differently for numerous reasons (differences in body mass, height, and shape, pregnancy, metabolic differences), and activity. 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. 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. 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

The average relative humidity in August in St. Louis is 70%.

Rainfall

In St. Louis, during 8.2 rainfall days, 2.99" (76mm) of precipitation is typically accumulated. In St. Louis, during the entire year, the rain falls for 112.6 days and collects up to 40.94" (1040mm) of precipitation.

Snowfall

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

Daylight

The average length of the day in August in St. Louis, Missouri, is 13h and 37min.
On the first day of the month, sunrise is at 6:02 am and sunset at 8:11 pm. On the last day of August, in St. Louis, Missouri, sunrise is at 6:29 am and sunset at 7:33 pm CDT.

Sunshine

The average sunshine in August in St. Louis is 8.7h.

UV index

The months with the highest UV index in St. Louis are June through August, with an average maximum UV index of 9. A UV Index estimate of 8 to 10 represents a very high health risk from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: The daily maximum UV index of 9 in August interpret into the following advice:
Take extra precautions. Fair-skinned individuals may get burned in less than 10 minutes. 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. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. 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.