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Will it freeze in Eureka in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 29°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 37°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 37°F Above 36°F · Chance Drizzle then Cloudy
- Fri, Nov 6 29°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 · Clear
- Tue, Nov 10 38°F Above 36°F · Mostly Clear
- Wed, Nov 11 39°F Above 36°F · Mostly Clear
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 Eureka
The median first fall hard-freeze date (28°F) is October 27, from NOAA’s 1991–2020 Climate Normals at Congerville 2NW. 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 18 · May 2 · May 18 | Sep 25 · Oct 6 · Oct 19 | 156 days |
| 32°F freeze | Apr 7 · Apr 21 · May 7 | Oct 3 · Oct 17 · Oct 30 | 178 days |
| 28°F hard freeze | Mar 28 · Apr 9 · Apr 27 | Oct 11 · Oct 27 · Nov 10 | 198 days |
Average high temperature by month
1991–2020 normals at Congerville 2NW
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 Eureka, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Congerville 2NW (station USC00111836, elevation 640 ft), 6.7 mi from Eureka. 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 Eureka
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Washington, IL | 8.1 mi | Apr 21 | Oct 17 |
| Morton, IL | 12 mi | Apr 21 | Oct 17 |
| East Peoria, IL | 14 mi | Apr 16 | Oct 23 |
| Peoria Heights, IL | 16 mi | Apr 16 | Oct 23 |
| Peoria, IL | 18 mi | Apr 16 | Oct 23 |
| Chillicothe, IL | 18 mi | Apr 20 | Oct 17 |
| Normal, IL | 20 mi | Apr 25 | Oct 16 |
| Bartonville, IL | 21 mi | Apr 16 | Oct 23 |
| Pekin, IL | 21 mi | Apr 16 | Oct 23 |
| Bloomington, IL | 23 mi | Apr 25 | Oct 16 |
Frequently asked questions
When is the last frost in Eureka?
On average, the last spring frost (32°F) in Eureka is around April 21. In about 1 year in 10 it comes after May 7, and in 9 years in 10 it comes after April 7.
When is the first frost in Eureka?
The first fall frost (32°F) usually arrives around October 17. There’s a 10% chance of a freeze by October 3 and a 90% chance by October 30.
Can it frost in Eureka 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 2.
What growing zone is Eureka?
Eureka 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 61530. See growing zones in Illinois.
More: all Illinois frost dates · Illinois growing zones · frost vs. freeze