Frost dates in Chicago: last spring frost and first autumn frost
When is it safe to plant out in Chicago, and when does the first frost come? Dates from 45 years of nightly minimum temperatures (1981–2025), with how early or late they can fall.
Frost dates in Chicago and how sure they are
| Early year (1 in 10) | Typical (median) | Late year (1 in 10) | |
|---|---|---|---|
| Last spring frost | 27 March | 9 April | 20 April |
| First autumn frost | 1 November | 12 November | 27 November |
In a typical year the last frost in Chicago falls around 9 April and the first one around 12 November, leaving about 219 frost-free days (between 198 and 241 in 8 years out of 10). To be safe, plant tender crops after 20 April: by then the last frost has passed in 9 years out of 10. Bring them in before 1 November: in 1 year in 10 the first frost comes earlier.
Frost month by month in Chicago
| Month | Average low | Coldest night (avg) | Record low | Frost nights | Years with frost |
|---|---|---|---|---|---|
| January | -5.9 °C | -15.4 °C | -28.9 °C | 27.6 | 100% |
| February | -5 °C | -13.4 °C | -21.1 °C | 24.5 | 100% |
| March | -1 °C | -8.1 °C | -17.7 °C | 19.6 | 100% |
| April | 3.2 °C | -1.8 °C | -6.8 °C | 4 | 82% |
| May | 8 °C | 3.2 °C | -0.5 °C | 0 | 2% |
| June | 14 °C | 8.5 °C | 3.3 °C | 0 | 0% |
| July | 18.6 °C | 14.9 °C | 11 °C | 0 | 0% |
| August | 18.8 °C | 15.4 °C | 9.5 °C | 0 | 0% |
| September | 15.2 °C | 10 °C | 4.8 °C | 0 | 0% |
| October | 8.8 °C | 3 °C | -1.4 °C | 0.2 | 9% |
| November | 2.6 °C | -3.8 °C | -9.8 °C | 7.4 | 91% |
| December | -2.9 °C | -11.6 °C | -26.1 °C | 21.3 | 100% |
Frost here means a night minimum at or below 0 °C at 2 m. Frost nights is the average count per month; years with frost is how many years had at least one.
Frost alerts for your garden or field
LayEarth Business Agro sends an alert when the forecast low at your saved site drops below your threshold (0 °C by default), with frost risk, hours below zero and white or black frost for each forecast day. LayEarth Pro, from 9 USD a month, adds alerts for the places you follow.
Temperature map around Chicago
The live temperature layer of the map (NOAA GFS forecast): watch the cold nights coming hour by hour.
More for Chicago
Weather in Chicago now · Will it rain today in Chicago? · Open the temperature map on Chicago
Questions
- When is the last frost in Chicago?
- On average around 9 April. In an early year the last frost comes by 27 March, in a late one (1 year in 10) after 20 April.
- When is the first frost in Chicago?
- On average around 12 November. In 1 year in 10 it comes before 1 November, in a mild year not until 27 November.
- How long is the growing season in Chicago?
- About 219 frost-free days between the last spring frost and the first autumn frost, from 198 in a short year to 241 in a long one.
- When can I plant tomatoes in Chicago?
- Frost-tender plants such as tomatoes, peppers, beans and courgettes go out after the last frost: after 20 April the risk is down to 1 year in 10. Hardy crops can go earlier.
- How cold does it get in Chicago?
- The coldest night of winter averages -17.6 °C; the lowest since 1981 was -28.9 °C in 1982.
Frost dates nearby
Milwaukee · Indianapolis · Detroit · Cincinnati · St. Louis · Columbus
How these dates are computed
Daily minimum temperature at 2 m from NASA POWER (MERRA-2 reanalysis, public domain), 1981–2025, corrected from the ~50 km grid to the real altitude of Chicago (6.5 °C per km). For each year: the last night at or below 0 °C before midsummer and the first one after it; the dates are the median and the 10% / 90% of those years. A garden in a frost pocket or a city centre can differ by days. Live temperatures: the temperature layer of the map.