Old Capitol · Photo: Billwhittaker · CC BY-SA 3.0January in Iowa City bites harder than in 90% of U.S. towns
Peak summer warmth arrives in July, with afternoons near 85°. Seasons differ by 72°, from the coldest nights to the warmest afternoons. Precipitation is light here, less than falls on 70% of U.S. towns. Picnics, hikes and garden evenings come into their own from May to June and August to October, with highs of 63–83°.
A year in Iowa City at a glance
Each month’s typical high and low, and what it brings.
What stands out about Iowa City’s climate
Compared with towns across the U.S., with Iowa City’s place in Iowa State beside it.
What a year in Iowa City feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 162 frost-free days a year
In half of years the last 32° night comes by April 29 and the first by October 9. Frost and day counts come from NOAA’s station at Iowa City, IA, 3 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Iowa City’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −13°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 28 inches of snow a winter
Snow, measured at Iowa City, IA, falls mostly in January, February and December. Precipitation (rain plus melted snow) adds up to 38 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 109 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Iowa City
89% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Iowa City, IA.
Living with Iowa City’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
162 frost-free days in zone 5b. The last frost comes by Apr 29 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 9.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October. 55 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Iowa City from natural hazards, tornadoes are the largest share (38%); heat waves, cold waves, winter storms and ice storms together are 16%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Iowa City and its neighbors
Every town next door is within a degree of Iowa City in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Iowa City’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Iowa City, IA | 13° | 85° | 38" | 28" |
| Sandwich, IL | 15° | 84° | 37" | 28" |
| Edgerton, WI | 12° | 83° | 37" | 36" |
| Cedar Lake, IN | 17° | 84° | 40" | 27" |
| Bryan, OH | 18° | 84° | 37" | 29" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Iowa City averaged 0.7° warmer than the 1900s. The biggest change is in December (+1.9°).
A smaller shift than in 93% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Iowa City compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Iowa City’s place among Iowa State’s.
Iowa City weather by month
Highs, lows and precipitation from NOAA’s grid at Iowa City’s center; snow, wet days and snow on the ground from Iowa City, IA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 30° | 13° | 1.1" | 7.6" | 7 | 18 | 12° – 34° |
| February | 35° | 17° | 1.4" | 7.5" | 7 | 13 | 13° – 38° |
| March | 48° | 28° | 2.3" | 3.2" | 9 | 4 | 30° – 53° |
| April | 62° | 38° | 3.7" | 0.5" | 11 | 0 | 41° – 57° |
| May | 72° | 50° | 4.7" | 0.0" | 13 | 0 | 56° – 68° |
| June | 81° | 60° | 5.4" | 0.0" | 11 | 0 | 68° – 75° |
| July | 85° | 64° | 4.2" | 0.0" | 9 | 0 | 68° – 81° |
| August | 83° | 61° | 4.3" | 0.0" | 9 | 0 | 67° – 78° |
| September | 76° | 53° | 3.7" | 0.0" | 8 | 0 | 59° – 69° |
| October | 63° | 41° | 2.9" | 0.4" | 9 | 0 | 46° – 57° |
| November | 48° | 29° | 2.2" | 1.1" | 8 | 2 | 30° – 49° |
| December | 35° | 18° | 1.6" | 7.2" | 8 | 11 | 12° – 36° |
| Year | 60° | 39° | 37.5" | 27.5" | 109 | 48 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 13° to 38°. June is the most reliable, staying within 7°.
Where Iowa City’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Iowa City’s center.
- Snow: Iowa City, IA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Iowa City, IA, 3 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Iowa City’s climate
What is the weather like in Iowa City?
A typical July afternoon reaches 85°, a January night drops to 13°, and about 28 inches of snow falls in a normal winter. Colder January nights than 90% of U.S. towns; cooler July afternoons than 54% of U.S. towns.
How cold does it get in Iowa City in winter?
January nights average 13°. About 130 nights a year reach 32° or below and 10 reach 0° or below. In the coldest January of the last 30 years the month averaged 12°.
How much snow does Iowa City get?
About 28 inches in a normal winter at Iowa City, IA, most of it in January, February and December, with snow on the ground about 48 days a year.
How hot does it get in Iowa City?
July, with a typical high of 85° and a low of 64°. About 24 days a year reach 90° and 1 reach 100° (Iowa City, IA).
When is the first and last frost in Iowa City?
In half of years the last spring frost (32°) comes by April 29 and the first fall frost by October 9, about 162 frost-free days, at Iowa City, IA.
What growing zone is Iowa City in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −13°.
What is the best time of year to visit Iowa City?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Iowa City getting warmer?
Yes: 1991–2020 averaged 0.7° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 93% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Iowa City.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.