| 2023 Hardiness Zone: | Zone 10a: 30°F to 35°F | |
| 2012 Hardiness Zone: | Zone 9b: 25°F to 30°F Zone 10a: 30°F to 35°F | |
| 1990 Hardiness Zone: | Zone 10a: 30F to 35F | |
| Average First Frost Date: | No Frost | |
| Average Last Frost Date: | No Frost | |
| Koppen-Geiger Climate Zone: | Csa - Hot-Summer Mediterranean Climate | |
| Ecoregion: | ||
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 91 - 120 days Over 86°F |
Annual Climate Data for ZIP Code 91764 - Ontario, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 42 | 44 | 45 | 47 | 51 | 55 | 59 | 60 | 59 | 53 | 46 | 42 | 50 |
| Avg Max Temp (°F) | 66 | 68 | 69 | 74 | 77 | 85 | 92 | 92 | 88 | 81 | 72 | 67 | 77 |
| Avg Precip (In.) | 3.97 | 4.13 | 3.76 | .9 | .36 | .06 | .02 | .15 | .38 | .53 | 1.36 | 2.13 | 17.76 |