Checking current alerts… View NWS forecast and alerts.
Will it freeze in Algonquin 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 36°F. Frost possible.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
4 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 36°F Frost possible · Patchy Drizzle then Mostly Cloudy
- Fri, Nov 6 29°F Freeze · Mostly Clear
- Sat, Nov 7 33°F Frost possible · Partly Cloudy
- Sun, Nov 8 34°F Frost possible · Mostly Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 38°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 Algonquin
The median first fall hard-freeze date (28°F) is October 29, from NOAA’s 1991–2020 Climate Normals at Elgin. 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 6 · May 24 | Sep 24 · Oct 7 · Oct 21 | 152 days |
| 32°F freeze | Apr 12 · Apr 26 · May 12 | Oct 3 · Oct 18 · Oct 31 | 174 days |
| 28°F hard freeze | Apr 1 · Apr 14 · Apr 29 | Oct 15 · Oct 29 · Nov 12 | 197 days |
Average high temperature by month
1991–2020 normals at Elgin
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 Algonquin, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Elgin (station USC00112736, elevation 763 ft), 6.9 mi from Algonquin. 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 Algonquin
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Lake in the Hills, IL | 1.2 mi | Apr 25 | Oct 22 |
| Carpentersville, IL | 3.1 mi | Apr 26 | Oct 18 |
| West Dundee, IL | 3.7 mi | Apr 26 | Oct 18 |
| Gilberts, IL | 4.3 mi | Apr 26 | Oct 18 |
| Crystal Lake, IL | 5.0 mi | Apr 25 | Oct 22 |
| Cary, IL | 5.0 mi | May 1 | Oct 11 |
| Huntley, IL | 5.6 mi | Apr 25 | Oct 22 |
| Pingree Grove, IL | 7.5 mi | Apr 26 | Oct 18 |
| Elgin, IL | 8.1 mi | Apr 26 | Oct 18 |
| Lake Barrington, IL | 8.7 mi | Apr 29 | Oct 20 |
Frequently asked questions
When is the last frost in Algonquin?
On average, the last spring frost (32°F) in Algonquin is around April 26. In about 1 year in 10 it comes after May 12, and in 9 years in 10 it comes after April 12.
When is the first frost in Algonquin?
The first fall frost (32°F) usually arrives around October 18. There’s a 10% chance of a freeze by October 3 and a 90% chance by October 31.
Can it frost in Algonquin 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 6.
What growing zone is Algonquin?
Algonquin 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 60102. See growing zones in Illinois.
More: all Illinois frost dates · Illinois growing zones · UV index today in Algonquin · frost vs. freeze