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Will it freeze in Hartford 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.
6 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 · Mostly Clear
- Sat, Nov 7 32°F Freeze · Mostly Clear
- Sun, Nov 8 33°F Frost possible · Mostly Clear
- Mon, Nov 9 39°F Above 36°F · Mostly Clear
- Tue, Nov 10 35°F Frost possible · Partly Cloudy
- Wed, Nov 11 35°F Frost possible · 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 Hartford
The median first fall hard-freeze date (28°F) is October 15, from NOAA’s 1991–2020 Climate Normals at Hartford Wastewater Plant. 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 | May 5 · May 20 · Jun 2 | Sep 12 · Sep 25 · Oct 6 | 128 days |
| 32°F freeze | Apr 24 · May 8 · May 24 | Sep 20 · Oct 3 · Oct 16 | 148 days |
| 28°F hard freeze | Apr 11 · Apr 27 · May 12 | Sep 30 · Oct 15 · Oct 30 | 171 days |
Average high temperature by month
1991–2020 normals at Hartford Wastewater Plant
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 Hartford, WI come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Hartford Wastewater Plant (station USC00473453, elevation 961 ft), 1.8 mi from Hartford. 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 Hartford
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Slinger, WI | 5.0 mi | May 5 | Oct 5 |
| Richfield, WI | 9.3 mi | Apr 30 | Oct 16 |
| Jackson, WI | 11 mi | Apr 30 | Oct 15 |
| West Bend, WI | 12 mi | May 1 | Oct 12 |
| Lisbon, WI | 13 mi | Apr 30 | Oct 16 |
| Germantown, WI | 14 mi | May 6 | Oct 8 |
| Mayville, WI | 15 mi | May 1 | Oct 10 |
| Sussex, WI | 15 mi | Apr 30 | Oct 16 |
| Hartland, WI | 16 mi | May 1 | Oct 13 |
| Oconomowoc, WI | 16 mi | Apr 30 | Oct 12 |
Frequently asked questions
When is the last frost in Hartford?
On average, the last spring frost (32°F) in Hartford is around May 8. In about 1 year in 10 it comes after May 24, and in 9 years in 10 it comes after April 24.
When is the first frost in Hartford?
The first fall frost (32°F) usually arrives around October 3. There’s a 10% chance of a freeze by September 20 and a 90% chance by October 16.
Can it frost in Hartford 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 20.
What growing zone is Hartford?
Hartford 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 53027. See growing zones in Wisconsin.
More: all Wisconsin frost dates · Wisconsin growing zones · frost vs. freeze