Frost dates 2026–2027

Frost dates for Washington, Illinois

Median (50% chance) dates of the last and first 32°F frost, from NOAA 1991–2020 climate normals at Congerville 2NW, 12 mi away (close match).

Last spring frostApr 21
First fall frostOct 17
178 frost-free days
Last spring frostApr 211 year in 10 after May 7
First fall frostOct 171 year in 10 by Oct 3
Growing season178 daysbetween median 32°F dates
Hardiness zoneZone 6a−10 to −5°F average extreme low

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Will it freeze in Washington 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 40°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.

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 Washington

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.

TemperatureLast 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
NOAA NCEI U.S. Climate Normals 1991–2020, station USC00111836. How to read these probabilities.

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 Washington, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Congerville 2NW (station USC00111836, elevation 640 ft), 12 mi from Washington. 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 Washington

CityDistanceLast spring frostFirst fall frost
East Peoria, IL 6.2 mi Apr 16 Oct 23
Morton, IL 6.8 mi Apr 21 Oct 17
Peoria Heights, IL 7.5 mi Apr 16 Oct 23
Eureka, IL 8.1 mi Apr 21 Oct 17
Peoria, IL 9.9 mi Apr 16 Oct 23
Bartonville, IL 12 mi Apr 16 Oct 23
Pekin, IL 14 mi Apr 16 Oct 23
Chillicothe, IL 15 mi Apr 20 Oct 17
Normal, IL 27 mi Apr 25 Oct 16
Bloomington, IL 29 mi Apr 25 Oct 16

Frequently asked questions

When is the last frost in Washington?

On average, the last spring frost (32°F) in Washington 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 Washington?

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 Washington 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 Washington?

Washington 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 61571. See growing zones in Illinois.

More: all Illinois frost dates · Illinois growing zones · frost vs. freeze