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Will it freeze in Waterloo in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 27°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.
4 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 35°F Frost possible · Mostly Cloudy
- Fri, Nov 6 27°F Hard freeze · Partly Cloudy
- Sat, Nov 7 35°F Frost possible · Mostly Clear
- Sun, Nov 8 36°F Frost possible · Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 38°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 Waterloo
The median first fall hard-freeze date (28°F) is October 20, from NOAA’s 1991–2020 Climate Normals at Waterloo 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 23 · May 6 · May 17 | Sep 16 · Sep 30 · Oct 11 | 147 days |
| 32°F freeze | Apr 11 · Apr 27 · May 10 | Sep 26 · Oct 10 · Oct 21 | 165 days |
| 28°F hard freeze | Apr 3 · Apr 16 · May 2 | Oct 6 · Oct 20 · Oct 31 | 185 days |
Average high temperature by month
1991–2020 normals at Waterloo 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 Waterloo, IA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Waterloo Municipal Airport (station USW00094910, elevation 868 ft), 5.0 mi from Waterloo. 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 Waterloo
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Cedar Falls, IA | 5.6 mi | Apr 27 | Oct 10 |
| Waverly, IA | 17 mi | Apr 27 | Oct 10 |
| Independence, IA | 23 mi | Apr 30 | Oct 7 |
| Oelwein, IA | 25 mi | Apr 30 | Oct 9 |
| Vinton, IA | 28 mi | May 3 | Oct 3 |
| Marshalltown, IA | 42 mi | Apr 28 | Oct 7 |
| Charles City, IA | 43 mi | Apr 30 | Oct 6 |
| Hiawatha, IA | 45 mi | Apr 28 | Oct 12 |
| Manchester, IA | 45 mi | May 3 | Oct 4 |
| Iowa Falls, IA | 47 mi | Apr 28 | Oct 10 |
Frequently asked questions
When is the last frost in Waterloo?
On average, the last spring frost (32°F) in Waterloo is around April 27. In about 1 year in 10 it comes after May 10, and in 9 years in 10 it comes after April 11.
When is the first frost in Waterloo?
The first fall frost (32°F) usually arrives around October 10. There’s a 10% chance of a freeze by September 26 and a 90% chance by October 21.
Can it frost in Waterloo 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 6.
What growing zone is Waterloo?
Waterloo 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 50702. See growing zones in Iowa.
More: all Iowa frost dates · Iowa growing zones · UV index today in Waterloo · frost vs. freeze