USDA Hardiness Zone 5b
Frost Dates for 61240 — Coal Valley, Illinois
NOAA 1991–2020 normals from Moline Quad City International Airport, IL (592 ft), 5 miles west.
Updated
In Coal Valley, the last spring frost (32°F) is around April 24 in half of years and has passed by May 9 in nine years out of ten. The first fall frost comes around October 18, as early as October 4 one year in ten, leaving a typical freeze-free season of 176 days (NOAA, Moline Quad City International Airport, IL).
- Last spring frost
- April 24
- First fall frost
- October 18
- Growing season
- 176 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
- November 24
- Last snow
- March 24
- Winters with snow
- 100%
- Snow per year
- 36.1"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Coal Valley
Half of springs at Moline Quad City International Airport, IL see their last 32°F night by April 24; only one in ten is past it by April 9, and one in ten still has one after May 9. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 4 20%, and after May 9 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 18 in half of years, as early as October 4 one year in ten, and holds off past October 28 one year in ten. A hard freeze of 28°F follows 9 days later, around October 27; in spring the one-in-ten date for 28°F is April 30, 9 days before the 32°F one. The freeze-free season lasts 176 days in a typical year, shorter than at 73% of the 158 Illinois stations; it reaches 195 days one year in ten and falls short of 155 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 May 4, and return around October 7. Severe cold of 16°F or below comes every winter, usually between November 26 and March 12.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 20 | Apr 25 | Apr 29 | May 1 | May 4 | May 7 | May 10 | May 14 | May 19 |
| 32°F | Apr 9 | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 4 | May 9 |
| 28°F | Mar 30 | Apr 3 | Apr 6 | Apr 9 | Apr 12 | Apr 15 | Apr 18 | Apr 23 | Apr 30 |
| 24°F | Mar 15 | Mar 20 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 6 | Apr 9 | Apr 16 |
| 20°F | Mar 4 | Mar 9 | Mar 14 | Mar 17 | Mar 21 | Mar 24 | Mar 28 | Mar 31 | Apr 3 |
| 16°F | Feb 25 | Mar 1 | Mar 5 | Mar 8 | Mar 12 | Mar 15 | Mar 18 | Mar 22 | Mar 27 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 24 | Sep 29 | Oct 1 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 15 | Oct 20 |
| 32°F | Oct 4 | Oct 9 | Oct 13 | Oct 16 | Oct 18 | Oct 20 | Oct 22 | Oct 25 | Oct 28 |
| 28°F | Oct 15 | Oct 20 | Oct 23 | Oct 25 | Oct 27 | Oct 29 | Oct 31 | Nov 3 | Nov 7 |
| 24°F | Oct 25 | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 8 | Nov 12 | Nov 16 | Nov 22 |
| 20°F | Nov 3 | Nov 7 | Nov 10 | Nov 14 | Nov 17 | Nov 21 | Nov 24 | Nov 28 | Dec 3 |
| 16°F | Nov 9 | Nov 16 | Nov 20 | Nov 23 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 12 |
Freeze probabilities 1991–2020 at Moline Quad City International Airport, 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 61240 →Compare Coal Valley with another place →
Weather by month in Coal Valley
July is the warmest month at Moline Quad City International Airport, IL, averaging 86°F by day and 65°F at night; January is the coldest at 32°F and 15°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 30% of years.
Warmth for growing adds up to 3,449 growing degree days a year (base 50°F), fewer than at 54% of the 158 Illinois stations. 36% of them (1,231) have built up by the end of June, and July adds the most, 790. Precipitation totals 38.2 inches a year, most in June (5.0") and least in January (1.7"); May to September bring 55% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 32 | 15 | 1.7 | 100% | 29 | 0 |
| Feb | 37 | 19 | 1.8 | 100% | 25 | 3 |
| Mar | 50 | 30 | 2.6 | 100% | 20 | 37 |
| Apr | 63 | 40 | 3.8 | 97% | 6 | 136 |
| May | 74 | 51 | 4.7 | 30% | <1 | 394 |
| Jun | 83 | 61 | 5.0 | 0% | 0 | 661 |
| Jul | 86 | 65 | 4.2 | 0% | 0 | 790 |
| Aug | 84 | 63 | 4.0 | 0% | 0 | 725 |
| Sep | 78 | 54 | 3.3 | 6% | <1 | 484 |
| Oct | 65 | 43 | 2.8 | 94% | 5 | 185 |
| Nov | 50 | 31 | 2.3 | 100% | 17 | 32 |
| Dec | 37 | 21 | 2.0 | 100% | 27 | 3 |
Monthly normals 1991–2020 at Moline Quad City International Airport, IL (592 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, Rock Island L&D 15, IL, 9 miles northwest of Coal Valley, has a last frost 5 days earlier (April 19), a first frost 4 days later (October 22), a season 8 days longer.
When it snows in Coal Valley, Illinois
The first measurable snow (0.1 inch or more) in Coal Valley usually arrives around November 24, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Moline Quad City International Airport, IL, 5.2 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 31 days after the last snow.
Planting calendar for 61240
| When | What to do |
|---|---|
| February 13 – February 27 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 27 – March 13 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 27 – April 10 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 24 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 26 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 4 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 18 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 61240 is 5 miles from Moline Quad City International Airport, IL, which stands at 592 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 61265 (Moline). The 2023 USDA Plant Hardiness Zone Map lists ZIP 61240 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.