St. Louis weather in August: St. Louis, Missouri: normal highs, lows, rain and records for August
St. Louis in August has a normal high of 88°F and a normal low of 69°F, a daily mean of 79°F, falling from 90°F on the 1st to 86°F by the 31st. Measurable precipitation falls on 8 days in a normal August, 3.38 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 31°C and low of 21°C, 86 mm of precipitation in August.
- NOAA stationSt Louis Lambert International Airport
- Station IDUSW00013994
- Location38.75°N 90.37°W
- Elevation531 ft (162 m)
- From the center11 miles
- Population279,695
- Jan 40° 24°
- Feb 46° 28°
- Mar 57° 37°
- Apr 68° 47°
- May 77° 58°
- Jun 86° 67°
- Jul 90° 71°
- Aug 88° 69°
- Sep 81° 61°
- Oct 69° 49°
- Nov 56° 37°
- Dec 45° 29°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is St. Louis in August?
The normal high is 88°F and the normal low 69°F, for a daily mean of 78.8°F. August is 1.6°F cooler than July and 7.8°F warmer than September. August is the 2nd warmest month of the year in St. Louis and the 7th wettest. Across the month the normal high falls 4°F, from 90°F on August 1 to 86°F on August 31. From one year to the next August's mean temperature typically moves about 2.6°F either way (NOAA's standard deviation), so roughly two Augusts in three average between 76°F and 81°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 28%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 90°F | 71°F | 28% | 18% |
| August 8 | 89°F | 71°F | 28% | 18% |
| August 15 | 89°F | 70°F | 27% | 17% |
| August 22 | 88°F | 69°F | 27% | 17% |
| August 31 | 86°F | 66°F | 26% | 16% |
Every day of August: normal high, low and chance of precipitation (warmest afternoon August 1, coldest night August 31)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| August 1 | 90°F | 71°F | 28% | 18% | 14 h 10 min |
| August 2 | 90°F | 71°F | 28% | 18% | 14 h 10 min |
| August 3 | 90°F | 71°F | 28% | 18% | 14 h 10 min |
| August 4 | 90°F | 71°F | 28% | 18% | 14 h 10 min |
| August 5 | 89°F | 71°F | 28% | 18% | 14 h |
| August 6 | 89°F | 71°F | 28% | 18% | 14 h |
| August 7 | 89°F | 71°F | 28% | 18% | 14 h |
| August 8 | 89°F | 71°F | 28% | 18% | 14 h |
| August 9 | 89°F | 71°F | 28% | 18% | 14 h |
| August 10 | 89°F | 70°F | 28% | 18% | 13 h 50 min |
| August 11 | 89°F | 70°F | 28% | 18% | 13 h 50 min |
| August 12 | 89°F | 70°F | 28% | 18% | 13 h 50 min |
| August 13 | 89°F | 70°F | 28% | 17% | 13 h 50 min |
| August 14 | 89°F | 70°F | 27% | 17% | 13 h 50 min |
| August 15 | 89°F | 70°F | 27% | 17% | 13 h 40 min |
| August 16 | 89°F | 70°F | 27% | 17% | 13 h 40 min |
| August 17 | 89°F | 70°F | 27% | 17% | 13 h 40 min |
| August 18 | 88°F | 69°F | 27% | 17% | 13 h 40 min |
| August 19 | 88°F | 69°F | 27% | 17% | 13 h 30 min |
| August 20 | 88°F | 69°F | 27% | 17% | 13 h 30 min |
| August 21 | 88°F | 69°F | 27% | 17% | 13 h 30 min |
| August 22 | 88°F | 69°F | 27% | 17% | 13 h 30 min |
| August 23 | 88°F | 68°F | 26% | 17% | 13 h 30 min |
| August 24 | 88°F | 68°F | 26% | 17% | 13 h 20 min |
| August 25 | 87°F | 68°F | 26% | 17% | 13 h 20 min |
| August 26 | 87°F | 68°F | 26% | 17% | 13 h 20 min |
| August 27 | 87°F | 67°F | 26% | 17% | 13 h 20 min |
| August 28 | 87°F | 67°F | 26% | 17% | 13 h 10 min |
| August 29 | 86°F | 67°F | 26% | 17% | 13 h 10 min |
| August 30 | 86°F | 67°F | 26% | 16% | 13 h 10 min |
| August 31 | 86°F | 66°F | 26% | 16% | 13 h 10 min |
- Normal high
- 88°FAugust average
- Normal low
- 69°FAugust average
- Precipitation
- 3.38 inmonth total
- Days with precipitation
- 80.01 inch or more
- Days at 90°F or more
- 13
- Daylight
- 14 h 10 min to 13 h 10 minAugust 1 to August 31
- Days at 70°F or more
- 31
- Days at 80°F or more
- 29
- Sunshine
- 81%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00013994; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in St. Louis in August?
On a given August day the chance of 0.01 inch or more is 27% on average, highest around August 1 (28%). In all, 3.38 in falls on 8 days of a normal August, 1 of them with an inch or more.
In a normal August in St. Louis, 13 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00013994.
How humid and windy is St. Louis in August?
At 3 p.m. the normal temperature is 85°F with 49% relative humidity and a dew point of 64°F; at 6 a.m. it is 70°F with 83% humidity. The wind averages 7.0 mph, most often from the southeast in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 70°F | 64°F | 83% | 5.1 mph | 36% |
| 9 a.m. | 77°F | 65°F | 66% | 7.4 mph | 46% |
| noon | 83°F | 64°F | 53% | 8.3 mph | 30% |
| 3 p.m. | 85°F | 64°F | 49% | 9.0 mph | 30% |
| 6 p.m. | 82°F | 64°F | 55% | 8.7 mph | 34% |
| 9 p.m. | 77°F | 65°F | 67% | 6.7 mph | 57% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00013994. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for August in St. Louis?
The warmest August temperature on St. Louis's official record (since 1874) is 110°F, on August 9, 1934; the coldest is 47°F, on August 29, 1965. The wettest August brought 14.78 in (1946).
The August mean against the 1991-2020 normal of 78.8°F: 2021 81.1°F (+2.3), 2022 79.7°F (+0.9), 2023 79.5°F (+0.7), 2024 79.6°F (+0.8), 2025 77.7°F (−1.1), 2026 79.7°F (+0.9). 5 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 81.1°F | +2.3°F | 4.85 in |
| 2022 | 79.7°F | +0.9°F | 5.78 in |
| 2023 | 79.5°F | +0.7°F | 3.60 in |
| 2024 | 79.6°F | +0.8°F | 1.38 in |
| 2025 | 77.7°F | −1.1°F | 1.48 in |
| 2026 | 79.7°F | +0.9°F | 3.64 in |
Source: records: ACIS, NWS threaded record STLthr; recent months: ACIS, station USW00013994. Records and recent months use complete months only.
How does August in St. Louis compare across Missouri?
Across the 134 places PlainClimate covers in Missouri, August normal highs run from 83°F in Canton to 91°F in Malden; St. Louis's is 88°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.