GreenlyUnited States: frost dates by city
The average last spring frost and first autumn frost in 23 cities of United States, from ten years of weather. The last spring frost comes earliest in Phoenix and latest in Denver.
| City | Last spring frost | First autumn frost | Frost-free days |
|---|---|---|---|
| Los Angeles | none in ten years | none in ten years | — |
| Miami | none in ten years | none in ten years | — |
| San Francisco | none in ten years | none in ten years | — |
| Phoenix | 4 February | 29 December | 328 days |
| Houston | 17 February | 27 November | 283 days |
| Austin | 19 February | 13 December | 297 days |
| Dallas | 19 February | 5 December | 289 days |
| Atlanta | 15 March | 22 November | 252 days |
| Charlotte | 19 March | 13 November | 239 days |
| Seattle | 20 March | 24 November | 249 days |
| Nashville | 24 March | 14 November | 235 days |
| Portland | 26 March | 22 November | 241 days |
| Washington, D.C. | 31 March | 16 November | 230 days |
| New York | 3 April | 20 November | 231 days |
| Philadelphia | 3 April | 11 November | 222 days |
| St. Louis | 6 April | 4 November | 212 days |
| Kansas City | 7 April | 1 November | 208 days |
| Boston | 9 April | 13 November | 218 days |
| Chicago | 18 April | 6 November | 202 days |
| Detroit | 24 April | 7 November | 197 days |
| Salt Lake City | 24 April | 26 October | 185 days |
| Minneapolis | 28 April | 24 October | 179 days |
| Denver | 1 May | 15 October | 167 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.