USDA Hardiness Zone 6a
Frost Dates for 60652 — Chicago, Illinois
NOAA 1991–2020 normals from Chicago Midway Airport 3SW, IL (620 ft), 3 miles west.
Updated
In Chicago, the last spring frost (32°F) is around April 10 in half of years and has passed by April 26 in nine years out of ten. The first fall frost comes around November 1, as early as October 21 one year in ten, leaving a typical freeze-free season of 203 days (NOAA, Chicago Midway Airport 3SW, IL).
- Last spring frost
- April 10
- First fall frost
- November 1
- Growing season
- 203 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
- November 21
- Last snow
- April 1
- Winters with snow
- 100%
- Snow per year
- 38.8"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Chicago
Half of springs at Chicago Midway Airport 3SW, IL see their last 32°F night by April 10; only one in ten is past it by March 30, and one in ten still has one after April 26. Planting tender crops after April 17 leaves a 30% risk of a frost on them, after April 20 20%, and after April 26 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 November 1 in half of years, as early as October 21 one year in ten, and holds off past November 16 one year in ten. A hard freeze of 28°F follows 10 days later, around November 11; in spring the one-in-ten date for 28°F is April 14, 12 days before the 32°F one. The freeze-free season lasts 203 days in a typical year, longer than at 92% of the 158 Illinois stations; it reaches 224 days one year in ten and falls short of 183 one year in ten. On average 108 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 22, and return around October 22. Severe cold of 16°F or below comes every winter, usually between December 7 and March 3.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 9 | Apr 14 | Apr 17 | Apr 19 | Apr 22 | Apr 26 | Apr 29 | May 2 | May 6 |
| 32°F | Mar 30 | Apr 2 | Apr 5 | Apr 7 | Apr 10 | Apr 14 | Apr 17 | Apr 20 | Apr 26 |
| 28°F | Mar 15 | Mar 21 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 5 | Apr 8 | Apr 14 |
| 24°F | Mar 4 | Mar 9 | Mar 13 | Mar 17 | Mar 20 | Mar 24 | Mar 27 | Mar 31 | Apr 3 |
| 20°F | Feb 23 | Mar 1 | Mar 4 | Mar 7 | Mar 10 | Mar 13 | Mar 17 | Mar 21 | Mar 26 |
| 16°F | Feb 13 | Feb 20 | Feb 25 | Feb 28 | Mar 3 | Mar 6 | Mar 9 | Mar 13 | Mar 17 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 25 | Oct 27 | Oct 30 | Nov 3 |
| 32°F | Oct 21 | Oct 25 | Oct 28 | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 10 | Nov 16 |
| 28°F | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 22 | Nov 26 |
| 24°F | Nov 7 | Nov 11 | Nov 15 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 1 | Dec 6 |
| 20°F | Nov 13 | Nov 18 | Nov 22 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 10 | Dec 19 |
| 16°F | Nov 22 | Nov 28 | Dec 1 | Dec 3 | Dec 7 | Dec 11 | Dec 16 | Dec 21 | Dec 26 |
Freeze probabilities 1991–2020 at Chicago Midway Airport 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 60652 →Compare Chicago with another place →
Weather by month in Chicago
July is the warmest month at Chicago Midway Airport 3SW, IL, averaging 85°F by day and 68°F at night; January is the coldest at 33°F and 20°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 86% of years.
Warmth for growing adds up to 3,592 growing degree days a year (base 50°F), more than at 59% of the 158 Illinois stations. 33% of them (1,201) have built up by the end of June, and July adds the most, 826. Precipitation totals 40.9 inches a year, most in May (4.8") and least in February (2.1"); May to September bring 51% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 33 | 20 | 2.3 | 100% | 27 | 0 |
| Feb | 37 | 23 | 2.1 | 100% | 23 | 3 |
| Mar | 48 | 32 | 2.7 | 100% | 18 | 35 |
| Apr | 60 | 42 | 4.2 | 86% | 4 | 126 |
| May | 72 | 52 | 4.8 | 5% | 0 | 379 |
| Jun | 81 | 63 | 4.5 | 0% | 0 | 658 |
| Jul | 85 | 68 | 4.0 | 0% | 0 | 826 |
| Aug | 83 | 67 | 4.1 | 0% | 0 | 775 |
| Sep | 77 | 59 | 3.3 | 0% | 0 | 536 |
| Oct | 64 | 47 | 3.9 | 48% | 1 | 211 |
| Nov | 50 | 35 | 2.7 | 100% | 12 | 39 |
| Dec | 38 | 25 | 2.3 | 100% | 24 | 4 |
Monthly normals 1991–2020 at Chicago Midway Airport 3SW, IL (620 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, Chicago Midway Airport, IL, 4 miles northwest of Chicago, has a last frost 1 day later (April 11), a first frost 1 day earlier (October 31), a season 2 days shorter.
When it snows in Chicago, Illinois
The first measurable snow (0.1 inch or more) in Chicago usually arrives around November 21, and the last of the season around April 1. Those are the middle dates across the winters of 1991–2020 at Chicago Midway Airport 3SW, IL, 3.4 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 9 days after the last snow.
Planting calendar for 60652
| When | What to do |
|---|---|
| January 30 – February 13 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 13 – February 27 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 13 – March 27 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 10 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 1 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 60652 is 3 miles from Chicago Midway Airport 3SW, IL, which stands at 620 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 19 other ZIP codes share the station; its figures are presented in full for 60628 (Chicago). The 2023 USDA Plant Hardiness Zone Map lists ZIP 60652 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.