USDA Hardiness Zone 6b
Frost Dates for 60649 — Chicago, Illinois
NOAA 1991–2020 normals from Chicago Northerly Is, IL (583 ft), 7 miles north.
Updated
In Chicago, the last spring frost (32°F) is around April 10 in half of years and has passed by April 25 in nine years out of ten. The first fall frost comes around November 5, as early as October 24 one year in ten, leaving a typical freeze-free season of 208 days (NOAA, Chicago Northerly Is, IL).
- Last spring frost
- April 10
- First fall frost
- November 5
- Growing season
- 208 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
- 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 Northerly Is, IL see their last 32°F night by April 10; only one in ten is past it by March 29, and one in ten still has one after April 25. Planting tender crops after April 17 leaves a 30% risk of a frost on them, after April 20 20%, and after April 25 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 November 5 in half of years, as early as October 24 one year in ten, and holds off past November 20 one year in ten. A hard freeze of 28°F follows 10 days later, around November 15; in spring the one-in-ten date for 28°F is April 14, 11 days before the 32°F one. The freeze-free season lasts 208 days in a typical year, longer than at 98% of the 158 Illinois stations; it reaches 229 days one year in ten and falls short of 187 one year in ten. On average 97 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 13 days longer, to about April 23, and return around October 26. Severe cold of 16°F or below comes every winter, usually between December 10 and March 3.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 9 | Apr 13 | Apr 16 | Apr 19 | Apr 23 | Apr 26 | Apr 30 | May 3 | May 9 |
| 32°F | Mar 29 | Apr 3 | Apr 5 | Apr 8 | Apr 10 | Apr 14 | Apr 17 | Apr 20 | Apr 25 |
| 28°F | Mar 16 | Mar 22 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 5 | Apr 9 | Apr 14 |
| 24°F | Mar 5 | Mar 10 | Mar 13 | Mar 16 | Mar 19 | Mar 23 | Mar 27 | Mar 31 | Apr 3 |
| 20°F | Feb 22 | Mar 1 | Mar 4 | Mar 7 | Mar 10 | Mar 14 | Mar 17 | Mar 21 | Mar 27 |
| 16°F | Feb 11 | Feb 19 | Feb 25 | Feb 28 | Mar 3 | Mar 6 | Mar 9 | Mar 14 | Mar 18 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 12 | Oct 18 | Oct 21 | Oct 24 | Oct 26 | Oct 29 | Oct 31 | Nov 3 | Nov 7 |
| 32°F | Oct 24 | Oct 28 | Nov 1 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 20 |
| 28°F | Nov 2 | Nov 6 | Nov 9 | Nov 13 | Nov 15 | Nov 18 | Nov 22 | Nov 25 | Dec 1 |
| 24°F | Nov 9 | Nov 14 | Nov 18 | Nov 21 | Nov 24 | Nov 27 | Dec 1 | Dec 5 | Dec 10 |
| 20°F | Nov 17 | Nov 22 | Nov 26 | Nov 29 | Dec 1 | Dec 6 | Dec 9 | Dec 14 | Dec 19 |
| 16°F | Nov 25 | Nov 30 | Dec 3 | Dec 7 | Dec 10 | Dec 14 | Dec 18 | Dec 22 | Dec 27 |
Freeze probabilities 1991–2020 at Chicago Northerly Is, 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 60649 →Compare Chicago with another place →
Weather by month in Chicago
July is the warmest month at Chicago Northerly Is, IL, averaging 81°F by day and 67°F at night; January is the coldest at 32°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 85% of years.
Warmth for growing adds up to 3,106 growing degree days a year (base 50°F), fewer than at 78% of the 158 Illinois stations. 29% of them (904) have built up by the end of June, and July adds the most, 748.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 32 | 20 | 100% | 26 | 1 |
| Feb | 36 | 23 | 100% | 23 | 2 |
| Mar | 45 | 31 | 100% | 14 | 22 |
| Apr | 55 | 40 | 85% | 3 | 77 |
| May | 66 | 50 | 4% | 0 | 265 |
| Jun | 76 | 60 | 0% | 0 | 537 |
| Jul | 81 | 67 | 0% | 0 | 748 |
| Aug | 80 | 67 | 0% | 0 | 735 |
| Sep | 73 | 60 | 0% | 0 | 501 |
| Oct | 61 | 48 | 30% | <1 | 182 |
| Nov | 49 | 36 | 98% | 8 | 34 |
| Dec | 37 | 25 | 100% | 22 | 2 |
Monthly normals 1991–2020 at Chicago Northerly Is, IL (583 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, 10 miles west of Chicago, has a last frost 1 day later (April 11), a first frost 5 days earlier (October 31), a season 7 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, 10.8 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 60649
| 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 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 5 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 60649 is 7 miles from Chicago Northerly Is, IL, which stands at 583 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 34 other ZIP codes share the station; its figures are presented in full for 60618 (Chicago). The 2023 USDA Plant Hardiness Zone Map lists ZIP 60649 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.