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Will it freeze in Oswego in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 30°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 38°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
3 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 38°F Above 36°F · Areas Of Drizzle then Mostly Cloudy
- Fri, Nov 6 30°F Freeze · Mostly Clear
- Sat, Nov 7 32°F Freeze · Mostly Clear
- Sun, Nov 8 34°F Frost possible · Mostly Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 37°F Above 36°F · Partly Cloudy
- Wed, Nov 11 38°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 Oswego
The median first fall hard-freeze date (28°F) is November 2, from NOAA’s 1991–2020 Climate Normals at Aurora. 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 17 · May 1 · May 19 | Sep 29 · Oct 13 · Oct 25 | 164 days |
| 32°F freeze | Apr 5 · Apr 19 · May 4 | Oct 9 · Oct 23 · Nov 3 | 185 days |
| 28°F hard freeze | Mar 25 · Apr 8 · Apr 23 | Oct 21 · Nov 2 · Nov 16 | 207 days |
Average high temperature by month
1991–2020 normals at Aurora
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 Oswego, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Aurora (station USC00110338, elevation 660 ft), 6.9 mi from Oswego. 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 Oswego
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Montgomery, IL | 2.5 mi | Apr 19 | Oct 23 |
| Yorkville, IL | 5.0 mi | Apr 28 | Oct 13 |
| Aurora, IL | 6.2 mi | Apr 19 | Oct 23 |
| Plainfield, IL | 7.5 mi | Apr 20 | Oct 22 |
| Sugar Grove, IL | 8.7 mi | Apr 28 | Oct 13 |
| North Aurora, IL | 8.7 mi | Apr 19 | Oct 23 |
| Plano, IL | 9.9 mi | Apr 28 | Oct 13 |
| Naperville, IL | 9.9 mi | Apr 28 | Oct 16 |
| Batavia, IL | 11 mi | Apr 19 | Oct 23 |
| Bolingbrook, IL | 12 mi | Apr 20 | Oct 22 |
Frequently asked questions
When is the last frost in Oswego?
On average, the last spring frost (32°F) in Oswego is around April 19. In about 1 year in 10 it comes after May 4, and in 9 years in 10 it comes after April 5.
When is the first frost in Oswego?
The first fall frost (32°F) usually arrives around October 23. There’s a 10% chance of a freeze by October 9 and a 90% chance by November 3.
Can it frost in Oswego 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 1.
What growing zone is Oswego?
Oswego is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 60543. See growing zones in Illinois.
More: all Illinois frost dates · Illinois growing zones · UV index today in Oswego · frost vs. freeze