Climate averages 1991–2020
Iowa City weather
in August.
A warm, wet month: the 2nd warmest and the 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a warm month in Iowa City: daytime highs average 27.4°C and nights cool to about 18.4°C. By daytime temperature it is the 2nd warmest of the 12 months.
Expect about 96 mm of rain on roughly 9 days, which makes August a wet month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 51 min on an average August day.
The nearest other city in this atlas is Cedar Rapids (40 km away). In August its highs average 26.9°C, 0.5°C cooler than Iowa City, with 94 mm of rain.
Among the 498 cities listed in the United States, Iowa City ranks joint 361st of 498 for the warmest August highs and joint 370th of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Iowa City is 2.5°C cooler than that mean.
From August to September, average highs fall by 3.7°C to 23.7°C, and monthly rainfall rises from 96 mm to 99 mm.
The annual picture
August in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Iowa City climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.5°C-10.3°C | -10.3°C | 39 | 7.1 | 9.510 h |
| February | 1.1°C-8.2°C | -8.2°C | 46 | 6.5 | 10.611 h |
| March | 8.7°C-1.7°C | -1.7°C | 69 | 9.1 | 11.912 h |
| April | 15.5°C4.9°C | 4.9°C | 111 | 11.8 | 13.313 h |
| May | 21.4°C11.4°C | 11.4°C | 123 | 13.4 | 14.515 h |
| June | 26.3°C17.0°C | 17.0°C | 128 | 11.7 | 15.115 h |
| July | 28.2°C19.3°C | 19.3°C | 95 | 9.5 | 14.915 h |
| August, selected | 27.4°C18.4°C | 18.4°C | 96 | 9.1 | 13.914 h |
| September | 23.7°C14.2°C | 14.2°C | 99 | 8.1 | 12.513 h |
| October | 16.6°C7.6°C | 7.6°C | 74 | 8.6 | 11.111 h |
| November | 8.7°C0.3°C | 0.3°C | 59 | 7.6 | 9.910 h |
| December | 1.4°C-6.3°C | -6.3°C | 49 | 6.9 | 9.29 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Cedar Rapids in AugustUnited States · 40 kmHigh 26.9°C · Low 17.8°C · 94 mm rain
- Davenport in AugustUnited States · 81 kmHigh 27.6°C · Low 19.0°C · 90 mm rain
- Des Moines in AugustUnited States · 173 kmHigh 27.8°C · Low 18.6°C · 94 mm rain
- Peoria (Illinois), United States in AugustUnited States · 195 kmHigh 28.0°C · Low 19.4°C · 79 mm rain
- Rockford in AugustUnited States · 213 kmHigh 26.6°C · Low 17.7°C · 87 mm rain
- Madison in AugustUnited States · 235 kmHigh 26.1°C · Low 17.2°C · 95 mm rain
- Bloomington (Illinois), United States in AugustUnited States · 250 kmHigh 27.6°C · Low 18.7°C · 82 mm rain
- Springfield (Illinois), United States in AugustUnited States · 261 kmHigh 28.6°C · Low 19.5°C · 78 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Iowa City) is explained once on the Iowa City year overview and on the Sources, method and limits page.