Checking current alerts… View NWS forecast and alerts.
Will it freeze in Denison in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 32°F (Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST).
Tonight: forecast low 32°F. Freeze.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
3 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 32°F Freeze · Cloudy
- Fri, Nov 6 28°F Hard freeze · Mostly Cloudy
- Sat, Nov 7 34°F Frost possible · Mostly Clear
- Sun, Nov 8 38°F Above 36°F · Clear
- Mon, Nov 9 38°F Above 36°F · Clear
- Tue, Nov 10 40°F Above 36°F · Partly Cloudy
- Wed, Nov 11 40°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 Denison
The median first fall hard-freeze date (28°F) is October 22, from NOAA’s 1991–2020 Climate Normals at Denison. 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 24 · May 5 · May 16 | Sep 18 · Oct 1 · Oct 14 | 148 days |
| 32°F freeze | Apr 13 · Apr 27 · May 9 | Sep 27 · Oct 11 · Oct 25 | 166 days |
| 28°F hard freeze | Apr 3 · Apr 17 · Apr 30 | Oct 5 · Oct 22 · Nov 4 | 186 days |
Average high temperature by month
1991–2020 normals at Denison
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 Denison, IA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Denison (station USC00132171, elevation 1,401 ft), 1.9 mi from Denison. 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 Denison
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Carroll, IA | 25 mi | Apr 27 | Oct 10 |
| Storm Lake, IA | 44 mi | Apr 25 | Oct 13 |
| Atlantic, IA | 46 mi | Apr 30 | Oct 2 |
| Cherokee, IA | 52 mi | May 4 | Oct 4 |
| Blair, NE | 52 mi | Apr 22 | Oct 17 |
| Sergeant Bluff, IA | 58 mi | Apr 29 | Oct 7 |
| Council Bluffs, IA | 60 mi | Apr 18 | Oct 21 |
| South Sioux City, NE | 62 mi | Apr 29 | Oct 7 |
| Sioux City, IA | 63 mi | Apr 29 | Oct 7 |
| Omaha, NE | 63 mi | Apr 16 | Oct 18 |
Frequently asked questions
When is the last frost in Denison?
On average, the last spring frost (32°F) in Denison is around April 27. In about 1 year in 10 it comes after May 9, and in 9 years in 10 it comes after April 13.
When is the first frost in Denison?
The first fall frost (32°F) usually arrives around October 11. There’s a 10% chance of a freeze by September 27 and a 90% chance by October 25.
Can it frost in Denison 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 5.
What growing zone is Denison?
Denison is in USDA Plant Hardiness Zone 5a (average annual extreme minimum temperature −20 to −15°F), based on the 2023 USDA map for ZIP code 51442. See growing zones in Iowa.
More: all Iowa frost dates · Iowa growing zones · frost vs. freeze