St. Louis, MO weather in August
Expect hot, humid weather with some rain in St. Louis in August, with highs near 88°F and lows near 69°F. Rain falls on about 8 days. It is one of the warmest months in St. Louis.
- Normal high
- 88°F
- Normal low
- 69°F
- Wet days
- 8
- 3.4 in total
- Muggy days
- 19
- dew point 65°F+
How August changes from start to finish
| August 1 | August 31 | |
|---|---|---|
| Normal high | 90°F | 86°F |
| Normal low | 71°F | 66°F |
| Chance of a wet day | 28% | 26% |
| Sunrise / sunset | 6:02 am / 8:11 pm | 6:29 am / 7:33 pm |
| Daylight | 14.2 h | 13.1 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Central Time).
A typical August day
- 6 am71°Fdew point 66°F
- 9 am79°Fdew point 66°F
- Noon84°Fdew point 65°F
- 3 pm86°Fdew point 65°F
- 6 pm83°Fdew point 65°F
- 9 pm78°Fdew point 66°F
NOAA hourly normals (local standard time) from St Louis Lambert Intl Airport (13 mi away); average wind 7 mph; clear or few clouds in 30% of daytime hours, mostly cloudy or overcast in 42%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F2 of 31
- Hot dayshigh 90°F or more13 of 31
- Muggy daysdaily mean dew point 65°F or more19 of 31
- Wet daysat least 0.01 in of rain or melted snow8 of 31
- Notable rainat least 0.10 in5 of 31
- Freezing nightslow 32°F or below0 of 31
- Snow on the groundsnow depth 1 in or more0 of 31
Average days per August, counted from daily records for each year 1991-2020.
Rain in August
Normal precipitation is 3.4 in; a dry August brings about 2.1 in and a wet one about 4.4 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more.
How August varies from year to year
- Warmest August, 1991-20202007: average high 95°F
- Coolest August1992: average high 83°F
- Wettest August2015: 6.7 in
- Driest August1991: 1.0 in
- Highest reading105°F (August 15, 2007)
- Lowest reading51°F (August 15, 1992)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
August compared with July and September
| July | August | September | |
|---|---|---|---|
| Normal high | 90°F | 88°F | 81°F |
| Normal low | 71°F | 69°F | 61°F |
| Wet days | 9 | 8 | 7 |
| Comfortable days | 1 | 2 | 10 |
| Daylight | 14.6 h | 13.6 h | 12.4 h |
Highs change by -2°F from July and -7°F into September.
Nearby alternatives in August
- Cooler: Joliet, IL229 mi · high 82°F · 9 wet days
How St. Louis ranks in August
- Normal high162nd warmest of 378 cities; 4th of 7 in Missouri
- Wet days172nd driest of 378
- Comfortable days172nd most of 341
What to pack for St. Louis in August
- Light, breathable clothing – highs near 88°F and about 19 muggy days
- A rain jacket or umbrella – rain on about 8 days
Heating and cooling
August has 1 heating degree days and 428 cooling degree days (base 65°F), 7% of the year's total heating and cooling demand.
Questions
How hot is St. Louis in August?
The normal high is 88°F and the normal low is 69°F. From 1991 to 2020 the hottest August reading was 105°F (August 15, 2007).
Does it rain a lot in St. Louis in August?
About 8 days in August have at least 0.01 in of precipitation, and the normal total is 3.4 in. The wettest August in 1991-2020 was in 2015 (6.7 in); the driest was in 1991 (1.0 in).
Is August a good time to visit St. Louis?
August ranks 8th of 12 months on our comfort score for St. Louis (47 out of 100). It has about 2 comfortable days and about 13 days at 90°F or hotter. The best months are April and May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth, humidity and wind by hour and cloud cover: St Louis Lambert Intl Airport (USW00013994), 13 mi NW of the city center, 531 ft (67 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Frost dates: Cahokia St Louis Airport (USW00003960), 4.4 mi SSE of the city center, 413 ft (51 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Lambert-St Louis International Airport (724340-13994), 13 mi NW of the city center, 531 ft (67 ft higher than the city). Hourly observations, 1991-2020.