USDA Hardiness Zone 6a
Frost Dates for 62694 — Winchester, Illinois
NOAA 1991–2020 normals from Winchester, IL (551 ft), under a mile northeast.
Updated
In Winchester, the last spring frost (32°F) is around April 18 in half of years and has passed by May 5 in nine years out of ten. The first fall frost comes around October 20, as early as October 5 one year in ten, leaving a typical freeze-free season of 183 days (NOAA, Winchester, IL).
- Last spring frost
- April 18
- First fall frost
- October 20
- Growing season
- 183 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°C) coldest night
- First snow
- December 5
- Last snow
- March 14
- Winters with snow
- 100%
- Snow per year
- 18.2"
median, 1991–2020
median, 1991–2020
25 of 25 observed
NOAA normal
Frost risk by date in Winchester
Half of springs at Winchester, IL see their last 32°F night by April 18; only one in ten is past it by April 3, and one in ten still has one after May 5. Planting tender crops after April 24 leaves a 30% risk of a frost on them, after April 29 20%, and after May 5 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 79% of the 158 Illinois stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 20 in half of years, as early as October 5 one year in ten, and holds off past October 31 one year in ten. A hard freeze of 28°F follows 9 days later, around October 29; in spring the one-in-ten date for 28°F is April 22, 13 days before the 32°F one. The freeze-free season lasts 183 days in a typical year, shorter than at 53% of the 158 Illinois stations; it reaches 202 days one year in ten and falls short of 160 one year in ten. On average 122 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 12 days longer, to about April 30, and return around October 8. Severe cold of 16°F or below comes every winter, usually between December 1 and March 7.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 14 | Apr 19 | Apr 22 | Apr 26 | Apr 30 | May 2 | May 5 | May 9 | May 15 |
| 32°F | Apr 3 | Apr 8 | Apr 11 | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 29 | May 5 |
| 28°F | Mar 20 | Mar 27 | Mar 31 | Apr 2 | Apr 5 | Apr 8 | Apr 11 | Apr 15 | Apr 22 |
| 24°F | Mar 9 | Mar 14 | Mar 19 | Mar 23 | Mar 26 | Mar 29 | Apr 1 | Apr 4 | Apr 9 |
| 20°F | Feb 28 | Mar 5 | Mar 9 | Mar 13 | Mar 16 | Mar 19 | Mar 23 | Mar 27 | Apr 1 |
| 16°F | Feb 17 | Feb 25 | Mar 1 | Mar 4 | Mar 7 | Mar 11 | Mar 15 | Mar 18 | Mar 24 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 24 | Sep 29 | Oct 2 | Oct 6 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 21 |
| 32°F | Oct 5 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Oct 31 |
| 28°F | Oct 16 | Oct 21 | Oct 24 | Oct 27 | Oct 29 | Nov 1 | Nov 3 | Nov 7 | Nov 12 |
| 24°F | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 25 |
| 20°F | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 7 |
| 16°F | Nov 12 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 3 | Dec 7 | Dec 12 | Dec 19 |
Freeze probabilities 1991–2020 at Winchester, 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 62694 →Compare Winchester with another place →
Weather by month in Winchester
July is the warmest month at Winchester, IL, averaging 87°F by day and 65°F at night; January is the coldest at 36°F and 18°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 17% of years.
Warmth for growing adds up to 3,673 growing degree days a year (base 50°F), more than at 65% of the 158 Illinois stations. 36% of them (1,338) have built up by the end of June, and July adds the most, 804. Precipitation totals 40.5 inches a year, most in June (5.0") and least in February (2.1"); May to September bring 50% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 36 | 18 | 2.3 | 100% | 28 | 2 |
| Feb | 41 | 21 | 2.1 | 100% | 25 | 6 |
| Mar | 53 | 31 | 3.1 | 100% | 19 | 53 |
| Apr | 65 | 41 | 4.4 | 92% | 4 | 171 |
| May | 75 | 52 | 4.8 | 17% | <1 | 424 |
| Jun | 84 | 62 | 5.0 | 0% | 0 | 681 |
| Jul | 87 | 65 | 4.0 | 0% | 0 | 804 |
| Aug | 86 | 63 | 3.5 | 0% | 0 | 758 |
| Sep | 80 | 54 | 3.0 | 6% | 0 | 510 |
| Oct | 68 | 43 | 3.1 | 91% | 5 | 215 |
| Nov | 53 | 32 | 2.8 | 100% | 15 | 42 |
| Dec | 41 | 23 | 2.4 | 100% | 26 | 6 |
Monthly normals 1991–2020 at Winchester, IL (551 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, Jacksonville 2, IL, 14 miles northeast of Winchester, has a last frost 1 day earlier (April 17), a first frost 1 day later (October 21), a season 3 days longer.
When it snows in Winchester, Illinois
The first measurable snow (0.1 inch or more) in Winchester usually arrives around December 5, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at White Hall 1 E, IL, 13.7 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 35 days after the last snow.
Planting calendar for 62694
| When | What to do |
|---|---|
| February 7 – February 21 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 21 – March 7 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 21 – April 4 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 18 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 28 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 6 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 20 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 62694 is under a mile from Winchester, IL, which stands at 551 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 62694 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°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.