GreenlyChicago: frost dates
United States
In Chicago the last spring frost usually comes around 18 April and the first autumn frost around 6 November, which leaves about 202 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground around 9 May.
| Last spring frost | around 18 April |
|---|---|
| First autumn frost | around 6 November |
| Frost-free days | 202 days |
Median of 2016–2025 for the 25 km grid cell of the city: the last day at or below 0 °C in spring and the first in autumn (ERA5 reanalysis via Open-Meteo). In a cold year a frost can come a week or two later — Greenly warns 48 hours ahead.
When to sow and plant
| Crop | Sow for seedlings | Plant out in a greenhouse | Open ground |
|---|---|---|---|
| Achocha | 23 February | 4 April | 25 April |
| Arugula | — | 7 March | sow 28 March |
| Basil | 30 March | 7 May | 28 May |
| Beet | — | 7 March | sow 28 March |
| Bell Pepper | 22 February | 7 May | 28 May |
| Black-eyed Susan | 22 February | — | 25 April |
| Bok Choy | 28 February | 4 April | 25 April |
| Broad bean | — | 7 March | sow 28 March |
| Broccoli | — | 7 March | sow 28 March |
| Brussels Sprouts | 21 January | 7 March | 28 March |
| Cabbage | — | 7 March | sow 28 March |
| Calendula | — | 7 March | sow 28 March |
| Carrot | — | — | sow 28 March |
| Cauliflower | 24 January | 7 March | 28 March |
| Celeriac | 17 January | 4 April | 25 April |
| Celery | 17 January | 4 April | 25 April |
| Celosia | 14 March | 28 April | 19 May |
| Chamomile | — | 7 March | sow 28 March |
| Chayote | 6 January | 4 April | 25 April |
| Chickpea | — | — | sow 28 March |
| Chili Pepper | 24 February | 9 May | 30 May |
| China aster | 16 March | 7 May | 28 May |
| Chives | — | — | sow 28 March |
| Cilantro | — | 7 March | sow 28 March |
| Corn | — | 4 April | sow 25 April |
| Cosmos | 14 March | 28 April | 19 May |
| Cucumber | 26 March | 7 May | 28 May |
| Daikon | — | 7 March | sow 28 March |
| Delphinium | 28 January | — | 28 March |
| Dill | — | 7 March | sow 28 March |
| Eggplant | 26 February | 7 May | 28 May |
| Florence fennel | 18 February | 4 April | 25 April |
| Garden sorrel | — | 7 March | sow 28 March |
| Green Beans | 26 February | 4 April | 25 April |
| Hyssop | — | — | sow 28 March |
| Kale | — | 7 March | sow 28 March |
| Kiwano | 17 March | 18 April | 9 May |
| Kohlrabi | — | 7 March | sow 28 March |
| Leek | 27 December | 7 March | 28 March |
| Lemon balm | — | 7 March | sow 28 March |
| Lettuce | — | 7 March | sow 28 March |
| Lisianthus | 10 December | 7 March | 28 March |
| Lovage | — | — | sow 28 March |
| Luffa | 26 March | 7 May | 28 May |
| Marigold | 21 February | 4 April | 25 April |
| Melon | 16 March | 7 May | 28 May |
| Microgreens | — | 28 April | sow 19 May |
| Moringa | 15 March | 9 May | 30 May |
| Mustard greens | — | 7 March | sow 28 March |
| Napa cabbage | 2 March | 4 April | 25 April |
| Nasturtium | 25 February | 4 April | 25 April |
| Okra | 26 March | 7 May | 28 May |
| Oregano | 6 January | 7 March | 28 March |
| Pansy | 10 January | 7 March | 28 March |
| Parsley | — | 7 March | sow 28 March |
| Parsnip | — | — | sow 28 March |
| Peanut | 31 March | 7 May | 28 May |
| Peas | — | 7 March | sow 28 March |
| Petunia | 5 March | 7 May | 28 May |
| Physalis | 4 March | 18 April | 9 May |
| Pumpkin | 12 March | 18 April | 9 May |
| Purple coneflower | 25 January | — | 28 March |
| Radish | — | — | sow 28 March |
| Sage | 17 January | 7 March | 28 March |
| Snapdragon | 1 January | 7 March | 28 March |
| Spinach | — | 7 March | sow 28 March |
| Stevia | 28 February | 18 April | 9 May |
| Stock | — | 7 March | sow 28 March |
| Sunflower | — | 28 April | sow 19 May |
| Sweet Corn | — | 4 April | sow 25 April |
| Sweet pea | 24 January | 7 March | 28 March |
| Sweet William | — | — | sow 28 March |
| Swiss Chard | — | 7 March | sow 28 March |
| Thyme | — | 7 March | sow 28 March |
| Tomato | 20 February | 18 April | 9 May |
| Turnip | — | 7 March | sow 28 March |
| Watercress | — | 7 March | sow 28 March |
| Watermelon | 5 April | 7 May | 28 May |
| Zinnia | 4 April | 9 May | 30 May |
| Zucchini | 17 March | 18 April | 9 May |
Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day.
Chicago: weather for the next 7 days
Forecast by Open-Meteo. Nights at or below 0 °C are marked as frost.
Weather in Chicago by month
Average weather in Chicago over 2016–2025: the warmest month is July, the wettest July.
| Month | Day, °C | Night, °C | Rain, mm | Rainy days |
|---|---|---|---|---|
| January | 0.4 | -6.6 | 65 | 10 |
| February | 3.1 | -5.5 | 56 | 9 |
| March | 8.7 | 0.1 | 92 | 12 |
| April | 13.9 | 4.3 | 100 | 14 |
| May | 19.9 | 10.3 | 122 | 14 |
| June | 26.4 | 16.6 | 114 | 12 |
| July | 27.9 | 19.4 | 137 | 13 |
| August | 27.2 | 18.8 | 100 | 12 |
| September | 24.3 | 16.1 | 92 | 10 |
| October | 17.2 | 9.4 | 118 | 11 |
| November | 9.2 | 2 | 57 | 8 |
| December | 3.6 | -3.3 | 63 | 9 |
Average of the daily highs and lows, rain per month and days with at least 1 mm (ERA5 via Open-Meteo, the same grid cell as the frost dates).
Planted in autumn
| Crop | Plant around |
|---|---|
| Bearded Iris | 7 October |
| Crocus | 7 October |
| Daffodil | 7 October |
| Garlic | 7 October |
| Hyacinth | 7 October |
| Lily | 7 October |
| Peony | 7 October |
| Saffron | 7 October |
| Tulip | 7 October |
| Wild garlic | 7 October |
A month before the first autumn frost, so the roots grow before winter.