USDA Hardiness Zone 5b
Frost Dates for 61401 — Galesburg, Illinois
NOAA 1991–2020 normals from Galesburg, IL (761 ft), under a mile west.
Updated
In Galesburg, the last spring frost (32°F) is around April 20 in half of years and has passed by May 5 in nine years out of ten. The first fall frost comes around October 19, as early as October 4 one year in ten, leaving a typical freeze-free season of 180 days (NOAA, Galesburg, IL).
- Last spring frost
- April 20
- First fall frost
- October 19
- Growing season
- 180 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- December 1
- Last snow
- March 12
- Winters with snow
- 100%
- Snow per year
- 25.9"
median, 1991–2020
median, 1991–2020
26 of 26 observed
NOAA normal
Frost risk by date in Galesburg
Half of springs at Galesburg, IL see their last 32°F night by April 20; only one in ten is past it by April 6, and one in ten still has one after May 5. Planting tender crops after April 26 leaves a 30% risk of a frost on them, after April 30 20%, and after May 5 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 54% of the 158 Illinois stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 19 in half of years, as early as October 4 one year in ten, and holds off past October 30 one year in ten. A hard freeze of 28°F follows 9 days later, around October 28; in spring the one-in-ten date for 28°F is April 24, 11 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, shorter than at 60% of the 158 Illinois stations; it reaches 198 days one year in ten and falls short of 160 one year in ten. On average 129 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 10 days longer, to about April 30, and return around October 9. Severe cold of 16°F or below comes every winter, usually between November 24 and March 15.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 17 | Apr 21 | Apr 25 | Apr 28 | Apr 30 | May 4 | May 6 | May 10 | May 15 |
| 32°F | Apr 6 | Apr 11 | Apr 15 | Apr 17 | Apr 20 | Apr 22 | Apr 26 | Apr 30 | May 5 |
| 28°F | Mar 28 | Apr 2 | Apr 5 | Apr 7 | Apr 10 | Apr 12 | Apr 16 | Apr 19 | Apr 24 |
| 24°F | Mar 18 | Mar 22 | Mar 27 | Mar 30 | Apr 1 | Apr 4 | Apr 6 | Apr 10 | Apr 15 |
| 20°F | Mar 7 | Mar 12 | Mar 17 | Mar 20 | Mar 23 | Mar 27 | Mar 31 | Apr 3 | Apr 8 |
| 16°F | Feb 28 | Mar 4 | Mar 8 | Mar 11 | Mar 15 | Mar 18 | Mar 21 | Mar 25 | Mar 30 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 25 | Sep 30 | Oct 3 | Oct 6 | Oct 9 | Oct 11 | Oct 14 | Oct 17 | Oct 21 |
| 32°F | Oct 4 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Oct 30 |
| 28°F | Oct 14 | Oct 19 | Oct 23 | Oct 25 | Oct 28 | Oct 30 | Nov 1 | Nov 4 | Nov 8 |
| 24°F | Oct 24 | Oct 28 | Oct 31 | Nov 2 | Nov 4 | Nov 7 | Nov 10 | Nov 15 | Nov 20 |
| 20°F | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 21 | Nov 26 | Dec 1 |
| 16°F | Nov 8 | Nov 13 | Nov 17 | Nov 21 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 11 |
Freeze probabilities 1991–2020 at Galesburg, IL, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 61401 →Compare Galesburg with another place →
Weather by month in Galesburg
July is the warmest month at Galesburg, IL, averaging 84°F by day and 65°F at night; January is the coldest at 30°F and 14°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 18% of years.
Warmth for growing adds up to 3,330 growing degree days a year (base 50°F), fewer than at 63% of the 158 Illinois stations. 36% of them (1,190) have built up by the end of June, and July adds the most, 766. Precipitation totals 39.0 inches a year, most in May (5.3") and least in January (1.7"); May to September bring 56% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 14 | 1.7 | 100% | 29 | 0 |
| Feb | 35 | 17 | 1.9 | 100% | 25 | 2 |
| Mar | 48 | 28 | 2.4 | 100% | 21 | 32 |
| Apr | 61 | 40 | 3.8 | 97% | 6 | 130 |
| May | 72 | 52 | 5.3 | 18% | <1 | 378 |
| Jun | 81 | 62 | 4.6 | 0% | 0 | 648 |
| Jul | 84 | 65 | 4.0 | 0% | 0 | 766 |
| Aug | 82 | 63 | 3.9 | 0% | 0 | 708 |
| Sep | 76 | 55 | 3.9 | 6% | 0 | 467 |
| Oct | 63 | 43 | 2.8 | 93% | 4 | 171 |
| Nov | 48 | 30 | 2.6 | 100% | 18 | 27 |
| Dec | 35 | 20 | 2.1 | 100% | 27 | 2 |
Monthly normals 1991–2020 at Galesburg, IL (761 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Knoxville, IL, 5 miles southeast of Galesburg, has a last frost 1 day later (April 21), a first frost 1 day later (October 20), a season 1 day longer.
When it snows in Galesburg, Illinois
The first measurable snow (0.1 inch or more) in Galesburg usually arrives around December 1, and the last of the season around March 12. Those are the middle dates across the winters of 1991–2020 at Galesburg, IL, 0.9 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 39 days after the last snow.
Planting calendar for 61401
| When | What to do |
|---|---|
| February 9 – February 23 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 23 – March 9 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 23 – April 6 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 20 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 27 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 5 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 19 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 61401 is under a mile from Galesburg, IL, which stands at 761 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 61401 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.