Chicago weather in August: Chicago, Illinois: normal highs, lows, rain and records for August
Chicago in August has a normal high of 83°F and a normal low of 65°F, a daily mean of 74°F, falling from 84°F on the 1st to 80°F by the 31st. Measurable precipitation falls on 9 days in a normal August, 4.25 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 28°C and low of 18°C, 108 mm of precipitation in August.
- NOAA stationChicago O'Hare International Airport
- Station IDUSW00094846
- Location41.99°N 87.93°W
- Elevation658 ft (201 m)
- From the center17 miles
- Population2,721,308
- Jan 32° 19°
- Feb 36° 22°
- Mar 47° 31°
- Apr 59° 40°
- May 71° 51°
- Jun 80° 61°
- Jul 85° 66°
- Aug 83° 65°
- Sep 76° 57°
- Oct 63° 45°
- Nov 48° 34°
- Dec 37° 24°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Chicago in August?
The normal high is 83°F and the normal low 65°F, for a daily mean of 73.8°F. August is 1.6°F cooler than July and 7.5°F warmer than September. August is the 2nd warmest month of the year in Chicago and the 2nd wettest. Across the month the normal high falls 4°F, from 84°F on August 1 to 80°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 71°F and 76°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 32%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 84°F | 67°F | 32% | 20% |
| August 8 | 83°F | 66°F | 31% | 20% |
| August 15 | 83°F | 66°F | 30% | 20% |
| August 22 | 82°F | 65°F | 30% | 20% |
| August 31 | 80°F | 63°F | 29% | 19% |
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 | 84°F | 67°F | 32% | 20% | 14 h 30 min |
| August 2 | 84°F | 66°F | 32% | 20% | 14 h 30 min |
| August 3 | 84°F | 66°F | 32% | 20% | 14 h 20 min |
| August 4 | 84°F | 66°F | 32% | 20% | 14 h 20 min |
| August 5 | 84°F | 66°F | 32% | 20% | 14 h 20 min |
| August 6 | 84°F | 66°F | 31% | 20% | 14 h 20 min |
| August 7 | 84°F | 66°F | 31% | 20% | 14 h 10 min |
| August 8 | 83°F | 66°F | 31% | 20% | 14 h 10 min |
| August 9 | 83°F | 66°F | 31% | 20% | 14 h 10 min |
| August 10 | 83°F | 66°F | 31% | 20% | 14 h 10 min |
| August 11 | 83°F | 66°F | 31% | 20% | 14 h 10 min |
| August 12 | 83°F | 66°F | 31% | 20% | 14 h |
| August 13 | 83°F | 66°F | 31% | 20% | 14 h |
| August 14 | 83°F | 66°F | 30% | 20% | 14 h |
| August 15 | 83°F | 66°F | 30% | 20% | 14 h |
| August 16 | 83°F | 65°F | 30% | 20% | 13 h 50 min |
| August 17 | 83°F | 65°F | 30% | 20% | 13 h 50 min |
| August 18 | 83°F | 65°F | 30% | 20% | 13 h 50 min |
| August 19 | 82°F | 65°F | 30% | 20% | 13 h 50 min |
| August 20 | 82°F | 65°F | 30% | 20% | 13 h 40 min |
| August 21 | 82°F | 65°F | 30% | 20% | 13 h 40 min |
| August 22 | 82°F | 65°F | 30% | 20% | 13 h 40 min |
| August 23 | 82°F | 64°F | 29% | 20% | 13 h 40 min |
| August 24 | 82°F | 64°F | 29% | 20% | 13 h 30 min |
| August 25 | 82°F | 64°F | 29% | 20% | 13 h 30 min |
| August 26 | 81°F | 64°F | 29% | 20% | 13 h 30 min |
| August 27 | 81°F | 64°F | 29% | 20% | 13 h 20 min |
| August 28 | 81°F | 63°F | 29% | 20% | 13 h 20 min |
| August 29 | 81°F | 63°F | 29% | 20% | 13 h 20 min |
| August 30 | 81°F | 63°F | 29% | 20% | 13 h 20 min |
| August 31 | 80°F | 63°F | 29% | 19% | 13 h 10 min |
- Normal high
- 83°FAugust average
- Normal low
- 65°FAugust average
- Precipitation
- 4.25 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 4
- Daylight
- 14 h 30 min to 13 h 10 minAugust 1 to August 31
- Days at 70°F or more
- 30
- Days at 80°F or more
- 21
- Sunshine
- 79%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00094846; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Chicago in August?
On a given August day the chance of 0.01 inch or more is 30% on average, highest around August 1 (32%). In all, 4.25 in falls on 9 days of a normal August, 1 of them with an inch or more.
In a normal August in Chicago, 4 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00094846.
How humid and windy is Chicago in August?
At 3 p.m. the normal temperature is 79°F with 52% relative humidity and a dew point of 60°F; at 6 a.m. it is 65°F with 84% humidity. The wind averages 8.0 mph, most often from the north-northeast in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 65°F | 60°F | 84% | 6.1 mph | 36% |
| 9 a.m. | 73°F | 61°F | 65% | 8.7 mph | 43% |
| noon | 78°F | 60°F | 53% | 9.9 mph | 27% |
| 3 p.m. | 79°F | 60°F | 52% | 10.8 mph | 29% |
| 6 p.m. | 75°F | 60°F | 59% | 9.7 mph | 36% |
| 9 p.m. | 70°F | 61°F | 73% | 7.0 mph | 52% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094846. 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 Chicago?
The warmest August temperature on Chicago's official record (since 1872) is 102°F, on August 5, 1918; the coldest is 42°F, on August 28, 1986. The wettest August brought 17.10 in (1987).
The August mean against the 1991-2020 normal of 73.8°F: 2021 77.2°F (+3.4), 2022 74.3°F (+0.5), 2023 74.3°F (+0.5), 2024 74.8°F (+1.0), 2025 73.3°F (−0.5), 2026 74.2°F (+0.4). 5 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 77.2°F | +3.4°F | 4.51 in |
| 2022 | 74.3°F | +0.5°F | 2.05 in |
| 2023 | 74.3°F | +0.5°F | 1.33 in |
| 2024 | 74.8°F | +1.0°F | 2.60 in |
| 2025 | 73.3°F | −0.5°F | 5.03 in |
| 2026 | 74.2°F | +0.4°F | 5.02 in |
Source: records: ACIS, NWS threaded record ORDthr; recent months: ACIS, station USW00094846. Records and recent months use complete months only.
How does August in Chicago 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; Chicago's is 83°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.