August weather forecast
St. Louis, MO

The last month of the summer, August, is another hot month in St. Louis, with temperature in the range of an average low of 69.4°F (20.8°C) and an average high of 88°F (31.1°C).

Temperature

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

Heat index

In August, the average heat index is evaluated at a torrid 100.2°F (37.9°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'feels like', 'apparent temperature', or 'felt air temperature', is a measure of how hot it feels when the actual air humidity is factored in. Additional factors like activity, clothing, metabolic differences, and pregnancy affect individual temperature impact. 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 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.
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. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 99.5°F (37.5°C) to 100.9°F (38.3°C), thermal conditions are potentially life-threatening.

Humidity

In August, the average relative humidity in St. Louis is 70%.

Rainfall

In St. Louis, it is raining for 8.2 days, with typically 2.99" (75.9mm) of accumulated precipitation. 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, Missouri.

Daylight

In August, the average length of the day in St. Louis 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, sunrise is at 6:29 am and sunset at 7:32 pm CDT.

Sunshine

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

UV index

June through August, with an average maximum UV index of 9, are months with the highest UV index in St. Louis, Missouri. A UV Index estimate of 8 to 10 represents a very high health hazard from unsafe exposure to UV radiation for the ordinary person.
Note: The average daily UV index of 9 in August 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. 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.