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Will it freeze in St. Marys in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Sat, Nov 7: 32°F (Sat, Nov 7, 6:00 PM EST to Sun, Nov 8, 6:00 AM EST).
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.
5 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 · Chance Light Rain
- Fri, Nov 6 36°F Frost possible · Mostly Cloudy
- Sat, Nov 7 32°F Freeze · Partly Cloudy
- Sun, Nov 8 34°F Frost possible · Mostly Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 36°F Frost possible · Mostly Clear
- Wed, Nov 11 36°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 St. Marys
The median first fall hard-freeze date (28°F) is October 31, from NOAA’s 1991–2020 Climate Normals at Celina 3 NE. 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 22 · May 5 · May 20 | Sep 22 · Oct 5 · Oct 19 | 153 days |
| 32°F freeze | Apr 12 · Apr 27 · May 10 | Oct 3 · Oct 19 · Nov 1 | 175 days |
| 28°F hard freeze | Apr 1 · Apr 15 · May 2 | Oct 17 · Oct 31 · Nov 13 | 199 days |
Average high temperature by month
1991–2020 normals at Celina 3 NE
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 St. Marys, OH come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Celina 3 NE (station USC00331390, elevation 866 ft), 7.7 mi from St. Marys. 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 St. Marys
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Celina, OH | 8.7 mi | Apr 27 | Oct 19 |
| Wapakoneta, OH | 11 mi | Apr 24 | Oct 24 |
| Lima, OH | 20 mi | Apr 24 | Oct 24 |
| Delphos, OH | 21 mi | Apr 21 | Oct 26 |
| Sidney, OH | 21 mi | Apr 27 | Oct 20 |
| Van Wert, OH | 24 mi | Apr 21 | Oct 26 |
| Piqua, OH | 29 mi | Apr 18 | Oct 23 |
| Portland, IN | 32 mi | Apr 28 | Oct 15 |
| Greenville, OH | 33 mi | Apr 21 | Oct 20 |
| Decatur, IN | 34 mi | Apr 23 | Oct 19 |
Frequently asked questions
When is the last frost in St. Marys?
On average, the last spring frost (32°F) in St. Marys 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 12.
When is the first frost in St. Marys?
The first fall frost (32°F) usually arrives around October 19. There’s a 10% chance of a freeze by October 3 and a 90% chance by November 1.
Can it frost in St. Marys 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 5.
What growing zone is St. Marys?
St. Marys 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 45885. See growing zones in Ohio.
More: all Ohio frost dates · Ohio growing zones · frost vs. freeze