August weather forecast
St. Louis, MO

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A beautiful twilight over the Gateway Arch in St. Louis, Missouri
A beautiful twilight over the Gateway Arch in St. Louis, Missouri

Weather in August

The weather in August carries forward the warmth and high humidity of July. Despite a slight dip in temperatures, the average remains notably high at 69.4°F. St. Louis continues to bask in long daylight hours, frequently punctuated by sudden bursts of summer rainstorms. The residency starts planning for the transition towards the autumn season. The prolonged summer augments the enjoyment of the city's many outdoor parks and amenities.

Temperature

August's advent in St. Louis notes a subtle adjustment in average high-temperature to a still tropical 88°F from July. St. Louis witnesses an average low-temperature of 69.4°F throughout the month of August.

Heat index

August's heat index is appraised at a sweltering 100.4°F. Incorporate extra safety measures to avoid heat exhaustion and heat cramps. Continuous activity could provoke heatstroke.
When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. Direct sunlight can cause a surge in the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'real feel', blends air temperature and moisture content to represent the felt temperature to humans. Factors such as metabolic variations, being pregnant, and physical activity can impact an individual's weather perception. Should you be directly under the sun, anticipate a possible increase in the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for babies and toddlers. Children often miss understanding the importance of rest and rehydration. Thirst usually appears late during dehydration - therefore, maintaining hydration, particularly during long physical activities, is essential.
Perspiration is the human body's physiological response to high temperatures and is an attempt to lower body temperature through evaporation of sweat. When air moisture content is high, the cooling process through evaporation is not as efficient, leading to an ineffective body cooling process and a feeling of overheating. Excessive heat gain, when not shed effectively by the body, can result in increasing body temperatures and related hazards.

Humidity

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

Rainfall

In St. Louis, Missouri, in August, during 8.2 rainfall days, 2.99" 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" 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, 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

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 vulnerability from unsafe exposure to UV radiation for average individuals.
Note: The daily high UV index of 9 in August translates into this advice:
Swift harm can befall unprotected skin and eyes. Prioritize safety. UV radiation from the sun is at its strongest between 10 a.m. and 4 p.m. Try to limit direct exposure during these hours. Boost your sun resistance with garments that are densely woven yet spacious. Applying and reapplying a broad-spectrum sunscreen with a minimum SPF 30 after every two hours, outdoor workout, or swim is recommended.
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FAQ

How hot is it in St. Louis in August?

During August, St. Louis experiences an average high-temperature of 88°F and a low-temperature of 69.4°F. The average heat index (a.k.a. 'apparent temperature', 'real feel'), which takes the relative humidity and factors it into the air temperature reading, in August is appraised at 100.4°F.

What is the average humidity in August in St. Louis?

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

How many days does it rain in August in St. Louis?

In St. Louis, during August, the rain falls for 8.2 days and regularly aggregates up to 2.99" of precipitation.

When it does not snow in St. Louis?

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

How many hours of daylight does St. Louis have in August?

In August, the average day length in St. Louis is 13h and 37min.

When are sunrise and sunset in August in St. Louis?

In August, on the first day of the month, sunrise is at 6:02 am and sunset at 8:11 pm. On the last day of the month, in St. Louis, sunrise is at 6:29 am and sunset at 7:33 pm CDT.

How long on average sun shines in August in St. Louis?

In St. Louis, the average sunshine duration in August is 8.7h.

What is the month with the highest UV index in St. Louis?

The months with the highest UV index are June through August, with an average maximum UV index of 9.

How high is the UV index in August in St. Louis?

The average daily maximum UV index in August in St. Louis, Missouri, is 9. A UV Index value of 8 to 10 symbolizes a very high health risk from unsafe exposure to Sun's UV rays.
Average high temperature
Average low temperature
Average humidity
Average rainfall
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average UV index

Average temperature in August
St. Louis, MO

Average temperature in August - St. Louis, MO
  • Average high temperature in August: 87.9°F

The warmest month (with the highest average high temperature) is July (89.1°F).
The month with the lowest average high temperature is January (39.9°F).

  • Average low temperature in August: 69.4°F

The month with the highest average low temperature is July (71°F).
The coldest month (with the lowest average low temperature) is January (23.7°F).

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Average humidity in August
St. Louis, MO

Average humidity in August - St. Louis, MO
  • Average humidity in August: 70%

The month with the highest relative humidity is December (75.8%).
The month with the lowest relative humidity is April (63.5%).

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Average rainfall in August
St. Louis, MO

Average rainfall in August - St. Louis, MO
  • Average rainfall in August: 3"

The wettest month (with the highest rainfall) is May (4.7").
The driest month (with the least rainfall) is February (2.2").

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Average rainfall days in August
St. Louis, MO

Average rainfall days in August - St. Louis, MO
  • Average rainfall days in August: 8.2 days

The month with the highest number of rainy days is May (11.9 days).
The month with the least rainy days is September (7.4 days).

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Average snowfall in August
St. Louis, MO

Average snowfall in August - St. Louis, MO
  • Average snowfall in August: 0"

The month with the highest snowfall is January (5.6").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in August
St. Louis, MO

Average snowfall days in August - St. Louis, MO
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is January (4.7 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in August /
Average sunshine in August
St. Louis, MO

Average daylight in August / Average sunshine in August - St. Louis, MO
  • Average daylight in August: 13h and 4min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in August: 8h and 4min

The month with the most sunshine is July (Average sunshine: 10h and 0min).
The month with the least sunshine is December (Average sunshine: 4h and 12min).

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Average UV index in August
St. Louis, MO

Average UV index in August - St. Louis, MO
  • Average UV index in August: 9

The months with the highest UV index are June, July and August (UV index 9).
The months with the lowest UV index are January and December (UV index 2).

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St. Louis, Missouri, USA

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