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Will it freeze in Ann Arbor in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Sat, Nov 7: 30°F (Sat, Nov 7, 6:00 PM EST to Sun, Nov 8, 6:00 AM EST).
Tonight: forecast low 39°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM EST to Fri, Nov 6, 6:00 AM EST.
5 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 39°F Above 36°F · Light Rain Likely
- Fri, Nov 6 34°F Frost possible · Chance Light Rain
- Sat, Nov 7 30°F Freeze · Partly Cloudy
- Sun, Nov 8 33°F Frost possible · Mostly Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 34°F Frost possible · Mostly Clear
- Wed, Nov 11 34°F Frost possible · Mostly 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 Ann Arbor
The median first fall hard-freeze date (28°F) is October 23, from NOAA’s 1991–2020 Climate Normals at Ann Arbor SE. 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 1 · May 15 · May 29 | Sep 18 · Oct 1 · Oct 12 | 137 days |
| 32°F freeze | Apr 21 · May 5 · May 20 | Sep 28 · Oct 10 · Oct 24 | 157 days |
| 28°F hard freeze | Apr 10 · Apr 24 · May 11 | Oct 7 · Oct 23 · Nov 6 | 180 days |
Average high temperature by month
1991–2020 normals at Ann Arbor SE
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 Ann Arbor, MI come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Ann Arbor SE (station USC00200228, elevation 832 ft), 3.0 mi from Ann Arbor. 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 Ann Arbor
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Ypsilanti, MI | 6.2 mi | May 5 | Oct 10 |
| Saline, MI | 7.5 mi | May 2 | Oct 11 |
| South Lyon, MI | 14 mi | May 5 | Oct 13 |
| Milan, MI | 14 mi | Apr 26 | Oct 19 |
| Chelsea, MI | 15 mi | Apr 30 | Oct 12 |
| Plymouth, MI | 15 mi | May 1 | Oct 17 |
| Northville, MI | 17 mi | May 1 | Oct 17 |
| Wayne, MI | 17 mi | Apr 20 | Oct 27 |
| Brighton, MI | 18 mi | May 6 | Oct 12 |
| Westland, MI | 18 mi | Apr 20 | Oct 27 |
Frequently asked questions
When is the last frost in Ann Arbor?
On average, the last spring frost (32°F) in Ann Arbor is around May 5. In about 1 year in 10 it comes after May 20, and in 9 years in 10 it comes after April 21.
When is the first frost in Ann Arbor?
The first fall frost (32°F) usually arrives around October 10. There’s a 10% chance of a freeze by September 28 and a 90% chance by October 24.
Can it frost in Ann Arbor 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 15.
What growing zone is Ann Arbor?
Ann Arbor is in USDA Plant Hardiness Zone 6a (average annual extreme minimum temperature −10 to −5°F), based on the 2023 USDA map for ZIP code 48104. See growing zones in Michigan.
More: all Michigan frost dates · Michigan growing zones · UV index today in Ann Arbor · frost vs. freeze