USDA Hardiness Zone 6b
Frost Dates for 62401 — Effingham, Illinois
NOAA 1991–2020 normals from Effingham 3SW, IL (625 ft), 4 miles west.
Updated
In Effingham, the last spring frost (32°F) is around April 13 in half of years and has passed by April 29 in nine years out of ten. The first fall frost comes around October 24, as early as October 9 one year in ten, leaving a typical freeze-free season of 191 days (NOAA, Effingham 3SW, IL).
- Last spring frost
- April 13
- First fall frost
- October 24
- Growing season
- 191 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- December 7
- Last snow
- March 1
- Winters with snow
- 100%
- Snow per year
- 14.6"
median, 1991–2020
median, 1991–2020
23 of 23 observed
NOAA normal
Frost risk by date in Effingham
Half of springs at Effingham 3SW, IL see their last 32°F night by April 13; only one in ten is past it by April 1, and one in ten still has one after April 29. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 23 20%, and after April 29 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 22% of the 158 Illinois stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 24 in half of years, as early as October 9 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 8 days later, around November 1; in spring the one-in-ten date for 28°F is April 17, 12 days before the 32°F one. The freeze-free season lasts 191 days in a typical year, longer than at 72% of the 158 Illinois stations; it reaches 211 days one year in ten and falls short of 170 one year in ten. On average 114 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 11 days longer, to about April 24, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 5 and March 3.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 10 | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 5 | May 11 |
| 32°F | Apr 1 | Apr 5 | Apr 7 | Apr 11 | Apr 13 | Apr 16 | Apr 19 | Apr 23 | Apr 29 |
| 28°F | Mar 17 | Mar 22 | Mar 27 | Mar 31 | Apr 2 | Apr 4 | Apr 7 | Apr 11 | Apr 17 |
| 24°F | Mar 4 | Mar 11 | Mar 15 | Mar 18 | Mar 22 | Mar 26 | Mar 30 | Apr 2 | Apr 7 |
| 20°F | Feb 22 | Feb 28 | Mar 4 | Mar 8 | Mar 12 | Mar 15 | Mar 18 | Mar 22 | Mar 29 |
| 16°F | Feb 9 | Feb 16 | Feb 24 | Feb 28 | Mar 3 | Mar 6 | Mar 10 | Mar 14 | Mar 19 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 29 | Oct 3 | Oct 8 | Oct 11 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 25 |
| 32°F | Oct 9 | Oct 15 | Oct 18 | Oct 22 | Oct 24 | Oct 26 | Oct 28 | Oct 31 | Nov 5 |
| 28°F | Oct 20 | Oct 25 | Oct 28 | Oct 31 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 19 |
| 24°F | Nov 1 | Nov 3 | Nov 6 | Nov 10 | Nov 13 | Nov 17 | Nov 21 | Nov 28 | Dec 2 |
| 20°F | Nov 8 | Nov 13 | Nov 17 | Nov 21 | Nov 25 | Nov 30 | Dec 3 | Dec 7 | Dec 14 |
| 16°F | Nov 15 | Nov 23 | Nov 28 | Dec 1 | Dec 5 | Dec 10 | Dec 15 | Dec 19 | Dec 24 |
Freeze probabilities 1991–2020 at Effingham 3SW, 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 62401 →Compare Effingham with another place →
Weather by month in Effingham
July is the warmest month at Effingham 3SW, IL, averaging 89°F by day and 66°F at night; January is the coldest at 37°F and 20°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month.
Warmth for growing adds up to 3,936 growing degree days a year (base 50°F), more than at 81% of the 158 Illinois stations. 37% of them (1,445) have built up by the end of June, and July adds the most, 845. Precipitation totals 44.0 inches a year, most in May (5.3") and least in February (2.4"); May to September bring 47% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 37 | 20 | 2.9 | 100% | 27 | 3 |
| Feb | 43 | 23 | 2.4 | 100% | 23 | 10 |
| Mar | 54 | 32 | 3.3 | 100% | 17 | 58 |
| Apr | 66 | 42 | 4.8 | 90% | 4 | 191 |
| May | 76 | 54 | 5.3 | 8% | <1 | 466 |
| Jun | 85 | 63 | 4.9 | 0% | 0 | 718 |
| Jul | 89 | 66 | 4.3 | 0% | 0 | 845 |
| Aug | 87 | 64 | 3.2 | 0% | 0 | 789 |
| Sep | 81 | 56 | 2.9 | 2% | 0 | 552 |
| Oct | 69 | 44 | 3.5 | 80% | 4 | 244 |
| Nov | 54 | 34 | 3.7 | 100% | 15 | 55 |
| Dec | 42 | 25 | 2.8 | 100% | 24 | 7 |
Monthly normals 1991–2020 at Effingham 3SW, IL (625 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, Neoga 4NW, IL, 16 miles north of Effingham, has a last frost 3 days later (April 16), a first frost 4 days earlier (October 20), a season 6 days shorter.
When it snows in Effingham, Illinois
The first measurable snow (0.1 inch or more) in Effingham usually arrives around December 7, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Effingham 3SW, IL, 3.5 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 43 days after the last snow.
Planting calendar for 62401
| When | What to do |
|---|---|
| February 2 – February 16 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 16 – March 2 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 16 – March 30 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 13 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 1 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 10 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 24 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 62401 is 4 miles from Effingham 3SW, IL, which stands at 625 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 62401 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°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.