When to plant in San Dimas, CA
Planting dates worked out from San Dimas's own frost records, not a generic zone chart.
Frost is rare in San Dimas: in 14 of the last 22 springs there was none at all. Frost dates matter less here than heat, so the planting table below is left out.
Safe to plant out
Feb 11
1 year in 10 has a later frost
Average last frost
Jan 12
about a 50% chance of a later one
Average first fall frost
Dec 23
1 year in 10 by Dec 1
Frost-free days
358
median, 1991–2020
Station used: Ontario Intl Ap · 22.0 km away · station 282 m, town 291 m. How we match towns to stations
San Dimas's weather over time
How the growing season has shifted here, year by year, from the station's own records.
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1999 | 321 |
| 2000 | 363 |
| 2001 | 363 |
| 2002 | 330 |
| 2003 | 359 |
| 2004 | 332 |
| 2005 | 363 |
| 2006 | 363 |
| 2007 | 347 |
| 2008 | 358 |
| 2009 | 363 |
| 2010 | 331 |
| 2011 | 281 |
| 2012 | 363 |
| 2013 | 328 |
| 2014 | 363 |
| 2015 | 320 |
| 2016 | 325 |
| 2017 | 363 |
| 2018 | 313 |
| 2019 | 363 |
| 2020 | 363 |
| 2021 | 363 |
| 2022 | 309 |
| 2023 | 363 |
| 2024 | 363 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1999 | 20.8 °C |
| 2000 | 22.8 °C |
| 2001 | 22.2 °C |
| 2002 | 21.9 °C |
| 2003 | 22.3 °C |
| 2004 | 22.6 °C |
| 2005 | 22.1 °C |
| 2006 | 23.3 °C |
| 2007 | 22.9 °C |
| 2008 | 23.4 °C |
| 2009 | 23.1 °C |
| 2010 | 21.4 °C |
| 2011 | 21.7 °C |
| 2012 | 23.6 °C |
| 2013 | 23.6 °C |
| 2014 | 24.1 °C |
| 2015 | 23.5 °C |
| 2016 | 23.4 °C |
| 2017 | 23.8 °C |
| 2018 | 23.6 °C |
| 2019 | 23.9 °C |
| 2020 | 24.2 °C |
| 2021 | 24.3 °C |
| 2022 | 24.1 °C |
| 2023 | 22.0 °C |
| 2024 | 23.0 °C |
What this means for you: This station's record is too short to show a reliable trend yet.
Source: daily records from Ontario Intl Ap (NOAA GHCN-Daily). Years with too many missing days are left out.