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Will it freeze in Sioux 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: 32°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 35°F. Frost possible.
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 35°F Frost possible · Cloudy
- Fri, Nov 6 32°F Freeze · Mostly Cloudy
- Sat, Nov 7 35°F Frost possible · Mostly Clear
- Sun, Nov 8 39°F Above 36°F · Clear
- Mon, Nov 9 38°F Above 36°F · Mostly Clear
- Tue, Nov 10 40°F Above 36°F · Partly Cloudy
- Wed, Nov 11 41°F Above 36°F · Partly Cloudy
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 Sioux City
The median first fall hard-freeze date (28°F) is October 18, from NOAA’s 1991–2020 Climate Normals at Sioux City Ang. 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 25 · May 7 · May 21 | Sep 18 · Sep 29 · Oct 11 | 144 days |
| 32°F freeze | Apr 15 · Apr 29 · May 11 | Sep 24 · Oct 7 · Oct 21 | 161 days |
| 28°F hard freeze | Apr 5 · Apr 19 · May 2 | Oct 2 · Oct 18 · Oct 30 | 180 days |
Average high temperature by month
1991–2020 normals at Sioux City Ang
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 Sioux City, IA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Sioux City Ang (station USC00137702, elevation 1,100 ft), 6.8 mi from Sioux 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 Sioux City
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| South Sioux City, NE | 2.5 mi | Apr 29 | Oct 7 |
| Sergeant Bluff, IA | 6.8 mi | Apr 29 | Oct 7 |
| Le Mars, IA | 22 mi | Apr 30 | Oct 4 |
| Vermillion, SD | 34 mi | May 3 | Oct 3 |
| Wayne, NE | 36 mi | Apr 29 | Oct 11 |
| Orange City, IA | 39 mi | Apr 30 | Oct 3 |
| Sioux Center, IA | 42 mi | Apr 30 | Oct 3 |
| Cherokee, IA | 46 mi | May 4 | Oct 4 |
| Sheldon, IA | 55 mi | May 5 | Sep 28 |
| Yankton, SD | 58 mi | Apr 27 | Oct 11 |
Frequently asked questions
When is the last frost in Sioux City?
On average, the last spring frost (32°F) in Sioux City is around April 29. In about 1 year in 10 it comes after May 11, and in 9 years in 10 it comes after April 15.
When is the first frost in Sioux City?
The first fall frost (32°F) usually arrives around October 7. There’s a 10% chance of a freeze by September 24 and a 90% chance by October 21.
Can it frost in Sioux 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 7.
What growing zone is Sioux City?
Sioux City 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 51101. See growing zones in Iowa.
More: all Iowa frost dates · Iowa growing zones · UV index today in Sioux City · frost vs. freeze