Checking current alerts… View NWS forecast and alerts.
Will it freeze in Lake Forest in the next 7 nights?
No overnight lows at or below 32°F are forecast in Lake Forest during the next 7 nights in the available NWS frost forecast.
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.
2 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 · Chance Rain Showers then Mostly Cloudy
- Fri, Nov 6 34°F Frost possible · Partly Cloudy
- Sat, Nov 7 36°F Frost possible · Partly Cloudy
- Sun, Nov 8 37°F Above 36°F · Mostly Clear
- Mon, Nov 9 42°F Above 36°F · Mostly Clear
- Tue, Nov 10 40°F Above 36°F · Partly Cloudy
- Wed, Nov 11 40°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 Lake Forest
The median first fall hard-freeze date (28°F) is November 1, from NOAA’s 1991–2020 Climate Normals at Chicago Botanic Garden. 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 24 · May 8 · May 26 | Sep 28 · Oct 10 · Oct 24 | 154 days |
| 32°F freeze | Apr 11 · Apr 26 · May 11 | Oct 5 · Oct 21 · Nov 2 | 176 days |
| 28°F hard freeze | Mar 31 · Apr 13 · Apr 28 | Oct 17 · Nov 1 · Nov 14 | 202 days |
Average high temperature by month
1991–2020 normals at Chicago Botanic Garden
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 Lake Forest, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Chicago Botanic Garden (station USC00111497, elevation 630 ft), 7.5 mi from Lake Forest. 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 Lake Forest
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Highwood, IL | 3.1 mi | Apr 26 | Oct 21 |
| Lake Bluff, IL | 3.1 mi | Apr 30 | Oct 19 |
| Lincolnshire, IL | 4.3 mi | Apr 19 | Oct 26 |
| Highland Park, IL | 4.3 mi | Apr 26 | Oct 21 |
| Deerfield, IL | 5.0 mi | Apr 26 | Oct 21 |
| Vernon Hills, IL | 5.6 mi | Apr 29 | Oct 20 |
| North Chicago, IL | 5.6 mi | Apr 30 | Oct 19 |
| Libertyville, IL | 6.8 mi | Apr 29 | Oct 20 |
| Buffalo Grove, IL | 7.5 mi | Apr 19 | Oct 26 |
| Northbrook, IL | 7.5 mi | Apr 26 | Oct 21 |
Frequently asked questions
When is the last frost in Lake Forest?
On average, the last spring frost (32°F) in Lake Forest is around April 26. In about 1 year in 10 it comes after May 11, and in 9 years in 10 it comes after April 11.
When is the first frost in Lake Forest?
The first fall frost (32°F) usually arrives around October 21. There’s a 10% chance of a freeze by October 5 and a 90% chance by November 2.
Can it frost in Lake Forest 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 8.
What growing zone is Lake Forest?
Lake Forest 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 60045. See growing zones in Illinois.
More: all Illinois frost dates · Illinois growing zones · frost vs. freeze