GreenlyFrost dates and when to plant in California
United States
In California the last spring frost comes between 12 January (Riverside) and 15 March (Santa Barbara) — the median of 2016–2025 in 8 cities. The first autumn frost comes between 3 December (Stockton) and 19 December (Riverside). The frost-free season lasts 275–341 days. 3 of the 11 cities had no frost at all. Tomato: plant out into open ground 24 February – 29 August, earliest in Riverside, latest in Riverside.
Frost dates by city in California
| City | Last spring frost | First autumn frost | Frost-free days | Climate zone | Tomato: window |
|---|---|---|---|---|---|
| Riverside | 12 January | 19 December | 341 | 270 frost-free days or more | 24 February – 29 August |
| Stockton | 4 February | 3 December | 302 | 270 frost-free days or more | 1 April – 13 August |
| Fresno | 5 February | 5 December | 303 | 270 frost-free days or more | 15 March – 15 August |
| Redding | 15 February | 11 December | 299 | 270 frost-free days or more | 14 April – 21 August |
| Bakersfield | 16 February | 14 December | 301 | 270 frost-free days or more | 16 March – 24 August |
| Sacramento | 18 February | 11 December | 296 | 270 frost-free days or more | 31 March – 21 August |
| San Jose | 24 February | none in ten years | — | Frost without a regular season | from 6 April |
| Santa Barbara | 15 March | 15 December | 275 | 270 frost-free days or more | 11 April – 25 August |
| Los Angeles | none in ten years | none in ten years | — | No frost in ten years | — |
| San Diego | none in ten years | none in ten years | — | No frost in ten years | — |
| San Francisco | none in ten years | none in ten years | — | No frost in ten years | — |
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 plant in California: windows by crop
The earliest start and the latest end among the cities here, each with its city; every city’s own window is on its page. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.
| Crop | Planting out or sowing |
|---|---|
| Tomato | 24 February (Riverside) – 29 August (Riverside) |
| Cucumber | 2 April (Bakersfield) – 4 October (Riverside) |
| Bell Pepper, Eggplant | 2 April (Bakersfield) – 29 August (Riverside) |
| Zucchini | 2 April (Bakersfield) – 2 October (Riverside) |
| Pumpkin | 2 April (Bakersfield) – 24 August (Riverside) |
| Watermelon | 2 April (Bakersfield) – 9 September (Riverside) |
| Peas | 22 December (Riverside) – 6 October (Riverside) |
| Garlic | Autumn planting: 3 November (Stockton) – end of December (Fresno) |
| Tulip, Daffodil, Crocus, Hyacinth | Autumn planting: by 5 November (Fresno) |
Weather by month in California
Across the 11 cities the warmest month is August (average days 18.4 … 39.5 °C) and the coldest December (average nights 4.3 … 9.7 °C). No city here averages below 0 °C at night in any month.
| Month | Day, °C | Night, °C | Rain, mm |
|---|---|---|---|
| January | 13.4 … 19.4 °C | 3.9 … 9.2 °C | 120 |
| February | 14.1 … 20.8 °C | 3.7 … 9.4 °C | 89 |
| March | 14.1 … 21.5 °C | 4.6 … 10.6 °C | 99 |
| April | 14.8 … 27.2 °C | 7.5 … 12.4 °C | 27 |
| May | 15.6 … 31.6 °C | 9.4 … 15.7 °C | 15 |
| June | 17.3 … 37.3 °C | 12.2 … 20.3 °C | 1 |
| July | 17.4 … 40.7 °C | 12.8 … 23.7 °C | 0 |
| August | 18.4 … 39.5 °C | 13.7 … 22.7 °C | 3 |
| September | 19.5 … 35.7 °C | 14.1 … 19 °C | 10 |
| October | 19.2 … 29.8 °C | 11.3 … 15.4 °C | 20 |
| November | 15.9 … 24.8 °C | 6.9 … 12 °C | 46 |
| December | 13.1 … 20.3 °C | 4.3 … 9.7 °C | 110 |
Day and night: the lowest … highest monthly average among the cities; rain: the middle city (ERA5 via Open-Meteo).
What to plant month by month: California
Other regions: United States
- Alabama
- Alaska
- Arizona
- Arkansas
- Colorado
- Connecticut
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York State
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington State
- West Virginia
- Wisconsin
More about the United States
- Gardening in the United States: climate zones and crops by region
- United States: frost dates by city
- When to plant tomatoes in the United States
- When to plant cucumbers in the United States
- When to plant bell peppers in the United States
- When to plant peas in the United States
- When to plant garlic in the United States
- Gardening by country
