Belleville weather in August: Belleville, Illinois: normal highs, lows, rain and records for August
Belleville in August has a normal high of 89°F and a normal low of 65°F, a daily mean of 77°F, falling from 90°F on the 1st to 87°F by the 31st. Measurable precipitation falls on 7 days in a normal August, 3.92 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 32°C and low of 19°C, 100 mm of precipitation in August.
- NOAA stationBelleville Siu Research
- Station IDUSW00013802
- Location38.52°N 89.85°W
- Elevation450 ft (137 m)
- From the center8 miles
- Population40,560
- Jan 43° 24°
- Feb 49° 28°
- Mar 59° 36°
- Apr 71° 46°
- May 79° 56°
- Jun 87° 65°
- Jul 90° 68°
- Aug 89° 65°
- Sep 83° 57°
- Oct 73° 47°
- Nov 58° 37°
- Dec 46° 28°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Belleville in August?
The normal high is 89°F and the normal low 65°F, for a daily mean of 77.2°F. August is 1.8°F cooler than July and 7.1°F warmer than September. August is the 2nd warmest month of the year in Belleville and the 5th wettest. Across the month the normal high falls 3°F, from 90°F on August 1 to 87°F on August 31. From one year to the next August's mean temperature typically moves about 2.5°F either way (NOAA's standard deviation), so roughly two Augusts in three average between 75°F and 80°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 24%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 90°F | 67°F | 24% | 18% |
| August 8 | 90°F | 67°F | 24% | 18% |
| August 15 | 89°F | 66°F | 23% | 17% |
| August 22 | 89°F | 64°F | 22% | 17% |
| August 31 | 87°F | 62°F | 22% | 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 | 67°F | 24% | 18% | 14 h 10 min |
| August 2 | 90°F | 67°F | 24% | 18% | 14 h 10 min |
| August 3 | 90°F | 67°F | 24% | 18% | 14 h 10 min |
| August 4 | 90°F | 67°F | 24% | 18% | 14 h 10 min |
| August 5 | 90°F | 67°F | 24% | 18% | 14 h |
| August 6 | 90°F | 67°F | 24% | 18% | 14 h |
| August 7 | 90°F | 67°F | 24% | 18% | 14 h |
| August 8 | 90°F | 67°F | 24% | 18% | 14 h |
| August 9 | 90°F | 67°F | 24% | 18% | 14 h |
| August 10 | 90°F | 67°F | 24% | 17% | 13 h 50 min |
| August 11 | 90°F | 66°F | 23% | 17% | 13 h 50 min |
| August 12 | 90°F | 66°F | 23% | 17% | 13 h 50 min |
| August 13 | 90°F | 66°F | 23% | 17% | 13 h 50 min |
| August 14 | 90°F | 66°F | 23% | 17% | 13 h 40 min |
| August 15 | 89°F | 66°F | 23% | 17% | 13 h 40 min |
| August 16 | 89°F | 66°F | 23% | 17% | 13 h 40 min |
| August 17 | 89°F | 65°F | 23% | 17% | 13 h 40 min |
| August 18 | 89°F | 65°F | 23% | 17% | 13 h 40 min |
| August 19 | 89°F | 65°F | 23% | 17% | 13 h 30 min |
| August 20 | 89°F | 65°F | 22% | 17% | 13 h 30 min |
| August 21 | 89°F | 65°F | 22% | 17% | 13 h 30 min |
| August 22 | 89°F | 64°F | 22% | 17% | 13 h 30 min |
| August 23 | 89°F | 64°F | 22% | 16% | 13 h 20 min |
| August 24 | 88°F | 64°F | 22% | 16% | 13 h 20 min |
| August 25 | 88°F | 64°F | 22% | 16% | 13 h 20 min |
| August 26 | 88°F | 64°F | 22% | 16% | 13 h 20 min |
| August 27 | 88°F | 63°F | 22% | 16% | 13 h 20 min |
| August 28 | 88°F | 63°F | 22% | 16% | 13 h 10 min |
| August 29 | 88°F | 63°F | 22% | 16% | 13 h 10 min |
| August 30 | 87°F | 62°F | 22% | 16% | 13 h 10 min |
| August 31 | 87°F | 62°F | 22% | 16% | 13 h 10 min |
- Normal high
- 89°FAugust average
- Normal low
- 65°FAugust average
- Precipitation
- 3.92 inmonth total
- Days with precipitation
- 70.01 inch or more
- Days at 90°F or more
- 14
- 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
- 83%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00013802; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Belleville in August?
On a given August day the chance of 0.01 inch or more is 23% on average, highest around August 1 (24%). In all, 3.92 in falls on 7 days of a normal August, 2 of them with an inch or more.
In a normal August in Belleville, 14 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00013802.
How humid and windy is Belleville in August?
At 3 p.m. the normal temperature is 85°F with 51% relative humidity and a dew point of 65°F; at 6 a.m. it is 66°F with 94% humidity. The wind averages 4.9 mph, most often from the south-southeast in the afternoon. A dew point of 65°F or more feels muggy to most people.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 66°F | 64°F | 94% | 3.0 mph | 60% |
| 9 a.m. | 76°F | 67°F | 73% | 6.0 mph | 61% |
| noon | 83°F | 66°F | 56% | 7.4 mph | 52% |
| 3 p.m. | 85°F | 65°F | 51% | 7.7 mph | 58% |
| 6 p.m. | 80°F | 66°F | 64% | 5.3 mph | 63% |
| 9 p.m. | 72°F | 67°F | 84% | 3.5 mph | 70% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00013802. 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 Belleville?
The warmest August temperature on this station's record (since 1948) is 105°F, on August 16, 2007; the coldest is 39°F, on August 29, 1986. The wettest August brought 10.43 in (2020).
The August mean against the 1991-2020 normal of 77.2°F: 2021 76.9°F (−0.3), 2022 75.3°F (−1.9), 2023 75.3°F (−1.9), 2024 75.2°F (−2.0), 2025 76.9°F (−0.3), 2026 78.9°F (+1.7). 1 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 76.9°F | −0.3°F | 2.45 in |
| 2022 | 75.3°F | −1.9°F | 1.47 in |
| 2023 | 75.3°F | −1.9°F | 5.75 in |
| 2024 | 75.2°F | −2.0°F | 0.90 in |
| 2025 | 76.9°F | −0.3°F | – |
| 2026 | 78.9°F | +1.7°F | – |
Source: records: ACIS, station USW00013802; recent months: ACIS, station USW00013802. Records and recent months use complete months only.
How does August in Belleville compare across Illinois?
Across the 144 places PlainClimate covers in Illinois, August normal highs run from 79°F in Barrington to 89°F in Anna; Belleville's is 89°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.