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Will it freeze in Iowa City in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 28°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 38°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
2 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 38°F Above 36°F · Mostly Cloudy
- Fri, Nov 6 28°F Hard freeze · Mostly Clear
- Sat, Nov 7 35°F Frost possible · Mostly Clear
- Sun, Nov 8 37°F Above 36°F · Clear
- Mon, Nov 9 42°F Above 36°F · Mostly Clear
- Tue, Nov 10 40°F Above 36°F · Partly Cloudy
- Wed, Nov 11 41°F Above 36°F · Mostly Clear
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Iowa City
The median first fall hard-freeze date (28°F) is October 28, from NOAA’s 1991–2020 Climate Normals at Iowa City Municipal Airport. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Apr 17 · May 1 · May 15 | Sep 26 · Oct 9 · Oct 21 | 161 days |
| 32°F freeze | Apr 5 · Apr 21 · May 6 | Oct 4 · Oct 18 · Oct 31 | 180 days |
| 28°F hard freeze | Mar 25 · Apr 9 · Apr 27 | Oct 15 · Oct 28 · Nov 9 | 202 days |
Average high temperature by month
1991–2020 normals at Iowa City Municipal Airport
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Iowa City, IA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Iowa City Municipal Airport (station USW00014937, elevation 650 ft), 1.7 mi from Iowa City. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Iowa City
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Coralville, IA | 4.3 mi | Apr 21 | Oct 18 |
| Tiffin, IA | 7.5 mi | Apr 21 | Oct 18 |
| North Liberty, IA | 7.5 mi | Apr 21 | Oct 18 |
| Cedar Rapids, IA | 22 mi | Apr 27 | Oct 11 |
| Washington, IA | 26 mi | Apr 28 | Oct 11 |
| Marion, IA | 27 mi | Apr 28 | Oct 12 |
| Hiawatha, IA | 29 mi | Apr 28 | Oct 12 |
| Muscatine, IA | 29 mi | Apr 24 | Oct 14 |
| Anamosa, IA | 34 mi | May 1 | Oct 4 |
| Vinton, IA | 43 mi | May 3 | Oct 3 |
Frequently asked questions
When is the last frost in Iowa City?
On average, the last spring frost (32°F) in Iowa City is around April 21. In about 1 year in 10 it comes after May 6, and in 9 years in 10 it comes after April 5.
When is the first frost in Iowa City?
The first fall frost (32°F) usually arrives around October 18. There’s a 10% chance of a freeze by October 4 and a 90% chance by October 31.
Can it frost in Iowa City after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after May 1.
What growing zone is Iowa City?
Iowa City is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 52242. See growing zones in Iowa.
More: all Iowa frost dates · Iowa growing zones · UV index today in Iowa City · frost vs. freeze