| 2023 Hardiness Zone: | Zone 9b: 25°F to 30°F 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 9b: 25F to 30F | |
| 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 91761 - Ontario, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 43 | 45 | 45 | 47 | 52 | 56 | 60 | 61 | 59 | 54 | 47 | 42 | 51 |
| Avg Max Temp (°F) | 67 | 69 | 70 | 75 | 78 | 85 | 91 | 92 | 88 | 81 | 73 | 68 | 78 |
| Avg Precip (In.) | 3.73 | 3.79 | 3.37 | .86 | .31 | .06 | .02 | .12 | .31 | .43 | 1.27 | 1.96 | 16.23 |