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Will it freeze in Altoona in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 29°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 · Cloudy
- Fri, Nov 6 29°F Freeze · Partly Cloudy
- Sat, Nov 7 36°F Frost possible · Mostly Clear
- Sun, Nov 8 39°F Above 36°F · Clear
- Mon, Nov 9 42°F Above 36°F · Clear
- Tue, Nov 10 41°F Above 36°F · Partly Cloudy
- Wed, Nov 11 42°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 Altoona
The median first fall hard-freeze date (28°F) is October 25, from NOAA’s 1991–2020 Climate Normals at Ankeny. 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 19 · May 3 · May 16 | Sep 21 · Oct 4 · Oct 18 | 155 days |
| 32°F freeze | Apr 8 · Apr 23 · May 6 | Sep 30 · Oct 15 · Oct 28 | 173 days |
| 28°F hard freeze | Mar 31 · Apr 13 · Apr 27 | Oct 11 · Oct 25 · Nov 5 | 193 days |
Average high temperature by month
1991–2020 normals at Ankeny
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 Altoona, IA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Ankeny (station USC00130241, elevation 975 ft), 10 mi from Altoona. 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 Altoona
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Bondurant, IA | 3.7 mi | Apr 23 | Oct 15 |
| Pleasant Hill, IA | 3.7 mi | Apr 18 | Oct 20 |
| Ankeny, IA | 8.1 mi | Apr 23 | Oct 15 |
| Des Moines, IA | 8.7 mi | Apr 18 | Oct 20 |
| Windsor Heights, IA | 12 mi | Apr 18 | Oct 20 |
| Johnston, IA | 13 mi | Apr 19 | Oct 18 |
| Polk City, IA | 16 mi | Apr 19 | Oct 18 |
| Urbandale, IA | 16 mi | Apr 19 | Oct 18 |
| Norwalk, IA | 16 mi | Apr 18 | Oct 20 |
| Clive, IA | 17 mi | Apr 18 | Oct 20 |
Frequently asked questions
When is the last frost in Altoona?
On average, the last spring frost (32°F) in Altoona is around April 23. In about 1 year in 10 it comes after May 6, and in 9 years in 10 it comes after April 8.
When is the first frost in Altoona?
The first fall frost (32°F) usually arrives around October 15. There’s a 10% chance of a freeze by September 30 and a 90% chance by October 28.
Can it frost in Altoona 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 3.
What growing zone is Altoona?
Altoona 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 50009. See growing zones in Iowa.
More: all Iowa frost dates · Iowa growing zones · frost vs. freeze