Climate averages 1991–2020
Iowa City weather
in May.
A mild, wet month: the 5th warmest and the 11th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in Iowa City: daytime highs average 21.4°C and nights cool to about 11.4°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 123 mm of rain on roughly 13 days, which makes May a wet month (the 11th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 30 min on an average May day.
The nearest other city in this atlas is Cedar Rapids (40 km away). In May its highs average 20.9°C, about as warm as Iowa City, with 126 mm of rain.
Among the 498 cities listed in the United States, Iowa City ranks joint 323rd of 498 for the warmest May highs and joint 452nd of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; Iowa City is 2.4°C cooler than that mean.
From May to June, average highs rise by 4.9°C to 26.3°C, and monthly rainfall rises from 123 mm to 128 mm.
The annual picture
May 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, selected | 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 | 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
May in nearby cities
- Cedar Rapids in MayUnited States · 40 kmHigh 20.9°C · Low 10.9°C · 126 mm rain
- Davenport in MayUnited States · 81 kmHigh 21.6°C · Low 12.0°C · 119 mm rain
- Des Moines in MayUnited States · 173 kmHigh 21.3°C · Low 11.7°C · 135 mm rain
- Peoria (Illinois), United States in MayUnited States · 195 kmHigh 22.1°C · Low 12.5°C · 117 mm rain
- Rockford in MayUnited States · 213 kmHigh 20.4°C · Low 10.3°C · 110 mm rain
- Madison in MayUnited States · 235 kmHigh 19.8°C · Low 9.6°C · 101 mm rain
- Bloomington (Illinois), United States in MayUnited States · 250 kmHigh 21.9°C · Low 11.9°C · 119 mm rain
- Springfield (Illinois), United States in MayUnited States · 261 kmHigh 22.7°C · Low 13.0°C · 117 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.