Frost dates in Denver: last spring frost and first autumn frost
When is it safe to plant out in Denver, 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 Denver and how sure they are
| Early year (1 in 10) | Typical (median) | Late year (1 in 10) | |
|---|---|---|---|
| Last spring frost | 18 April | 1 May | 14 May |
| First autumn frost | 23 September | 15 October | 2 November |
In a typical year the last frost in Denver falls around 1 May and the first one around 15 October, leaving about 169 frost-free days (between 143 and 190 in 8 years out of 10). To be safe, plant tender crops after 14 May: by then the last frost has passed in 9 years out of 10. Bring them in before 23 September: in 1 year in 10 the first frost comes earlier.
Frost month by month in Denver
| Month | Average low | Coldest night (avg) | Record low | Frost nights | Years with frost |
|---|---|---|---|---|---|
| January | -3.7 °C | -12.6 °C | -19.6 °C | 23.8 | 100% |
| February | -3.2 °C | -11.9 °C | -22 °C | 20.6 | 100% |
| March | -0.5 °C | -8.1 °C | -15 °C | 16.8 | 100% |
| April | 2.4 °C | -4.8 °C | -9.8 °C | 8.7 | 100% |
| May | 7.7 °C | 0.2 °C | -4.9 °C | 0.9 | 53% |
| June | 13.6 °C | 7.1 °C | 3.8 °C | 0 | 0% |
| July | 17.3 °C | 13 °C | 9.1 °C | 0 | 0% |
| August | 16.5 °C | 12.1 °C | 7.3 °C | 0 | 0% |
| September | 11.8 °C | 4.1 °C | -6.1 °C | 0.4 | 20% |
| October | 5.1 °C | -3.4 °C | -13.4 °C | 3.7 | 84% |
| November | 0 °C | -8 °C | -16.5 °C | 14.3 | 100% |
| December | -3.4 °C | -12.5 °C | -20.6 °C | 22.7 | 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 Denver
The live temperature layer of the map (NOAA GFS forecast): watch the cold nights coming hour by hour.
More for Denver
Weather in Denver now · Will it rain today in Denver? · Open the temperature map on Denver
Questions
- When is the last frost in Denver?
- On average around 1 May. In an early year the last frost comes by 18 April, in a late one (1 year in 10) after 14 May.
- When is the first frost in Denver?
- On average around 15 October. In 1 year in 10 it comes before 23 September, in a mild year not until 2 November.
- How long is the growing season in Denver?
- About 169 frost-free days between the last spring frost and the first autumn frost, from 143 in a short year to 190 in a long one.
- When can I plant tomatoes in Denver?
- Frost-tender plants such as tomatoes, peppers, beans and courgettes go out after the last frost: after 14 May the risk is down to 1 year in 10. Hardy crops can go earlier.
- How cold does it get in Denver?
- The coldest night of winter averages -15.9 °C; the lowest since 1981 was -22 °C in 2011.
Frost dates nearby
Albuquerque · Salt Lake City · Oklahoma City · Kansas City · El Paso · Las Vegas
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 Denver (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.