Checking current alerts… View NWS forecast and alerts.
Will it freeze in Harrisburg in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 32°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 42°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 42°F Above 36°F · Partly Cloudy
- Fri, Nov 6 32°F Freeze · Mostly Clear
- Sat, Nov 7 30°F Freeze · Mostly Clear
- Sun, Nov 8 33°F Frost possible · Clear
- Mon, Nov 9 37°F Above 36°F · Clear
- Tue, Nov 10 38°F Above 36°F · Mostly Clear
- Wed, Nov 11 39°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 Harrisburg
The median first fall hard-freeze date (28°F) is November 6, from NOAA’s 1991–2020 Climate Normals at Harrisburg. 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 3 · Apr 19 · May 5 | Oct 1 · Oct 16 · Oct 28 | 180 days |
| 32°F freeze | Mar 21 · Apr 7 · Apr 25 | Oct 10 · Oct 26 · Nov 8 | 202 days |
| 28°F hard freeze | Mar 7 · Mar 26 · Apr 12 | Oct 23 · Nov 6 · Nov 25 | 226 days |
Average high temperature by month
1991–2020 normals at Harrisburg
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 Harrisburg, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Harrisburg (station USC00113879, elevation 365 ft), 1.2 mi from Harrisburg. 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 Harrisburg
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Marion, IL | 22 mi | Apr 9 | Oct 22 |
| West Frankfort, IL | 24 mi | Apr 4 | Oct 28 |
| Herrin, IL | 27 mi | Apr 9 | Oct 22 |
| Benton, IL | 28 mi | Apr 4 | Oct 28 |
| Carterville, IL | 29 mi | Apr 9 | Oct 22 |
| Carbondale, IL | 37 mi | Apr 9 | Oct 22 |
| Mount Vernon, IN | 38 mi | Apr 7 | Oct 28 |
| Metropolis, IL | 42 mi | Apr 6 | Oct 27 |
| Du Quoin, IL | 42 mi | Apr 6 | Oct 22 |
| Murphysboro, IL | 43 mi | Apr 9 | Oct 22 |
Frequently asked questions
When is the last frost in Harrisburg?
On average, the last spring frost (32°F) in Harrisburg is around April 7. In about 1 year in 10 it comes after April 25, and in 9 years in 10 it comes after March 21.
When is the first frost in Harrisburg?
The first fall frost (32°F) usually arrives around October 26. There’s a 10% chance of a freeze by October 10 and a 90% chance by November 8.
Can it frost in Harrisburg 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 April 19.
What growing zone is Harrisburg?
Harrisburg is in USDA Plant Hardiness Zone 7a (average annual extreme minimum temperature 0 to 5°F), based on the 2023 USDA map for ZIP code 62965. See growing zones in Illinois.
More: all Illinois frost dates · Illinois growing zones · frost vs. freeze