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Will it freeze in Ontario in the next 7 nights?
No overnight lows at or below 32°F are forecast in Ontario during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 44°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM EST to Fri, Nov 6, 6:00 AM EST.
3 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 44°F Above 36°F · Mostly Cloudy
- Fri, Nov 6 36°F Frost possible · Slight Chance Light Rain
- Sat, Nov 7 33°F Frost possible · Partly Cloudy
- Sun, Nov 8 35°F Frost possible · Mostly Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 37°F Above 36°F · Mostly Clear
- Wed, Nov 11 37°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 Ontario
The median first fall hard-freeze date (28°F) is October 28, from NOAA’s 1991–2020 Climate Normals at Mansfield 5 W. 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 9 · May 27 | Sep 20 · Oct 4 · Oct 16 | 146 days |
| 32°F freeze | Apr 16 · Apr 30 · May 17 | Oct 1 · Oct 15 · Oct 29 | 167 days |
| 28°F hard freeze | Apr 4 · Apr 21 · May 7 | Oct 13 · Oct 28 · Nov 9 | 188 days |
Average high temperature by month
1991–2020 normals at Mansfield 5 W
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 Ontario, OH come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Mansfield 5 W (station USC00334874, elevation 1,350 ft), 0.1 mi from Ontario. 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 Ontario
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Mansfield, OH | 4.3 mi | Apr 26 | Oct 22 |
| Shelby, OH | 8.7 mi | Apr 30 | Oct 15 |
| Galion, OH | 8.7 mi | Apr 26 | Oct 20 |
| Ashland, OH | 17 mi | Apr 30 | Oct 15 |
| Bucyrus, OH | 19 mi | Apr 19 | Oct 27 |
| Willard, OH | 21 mi | Apr 25 | Oct 25 |
| Mount Vernon, OH | 27 mi | May 1 | Oct 10 |
| Marion, OH | 29 mi | Apr 25 | Oct 20 |
| Norwalk, OH | 33 mi | Apr 25 | Oct 25 |
| Upper Sandusky, OH | 35 mi | Apr 29 | Oct 17 |
Frequently asked questions
When is the last frost in Ontario?
On average, the last spring frost (32°F) in Ontario is around April 30. In about 1 year in 10 it comes after May 17, and in 9 years in 10 it comes after April 16.
When is the first frost in Ontario?
The first fall frost (32°F) usually arrives around October 15. There’s a 10% chance of a freeze by October 1 and a 90% chance by October 29.
Can it frost in Ontario 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 9.
What growing zone is Ontario?
Ontario 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 44906. See growing zones in Ohio.
More: all Ohio frost dates · Ohio growing zones · frost vs. freeze