| 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 9b: 25F to 30F | |
| Average First Frost Date: | Jan. 21 - Jan. 31 | |
| 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 91739 - Rancho Cucamonga, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 42 | 44 | 44 | 46 | 50 | 55 | 59 | 60 | 58 | 52 | 46 | 41 | 50 |
| Avg Max Temp (°F) | 65 | 67 | 69 | 74 | 78 | 86 | 93 | 93 | 89 | 80 | 71 | 66 | 78 |
| Avg Precip (In.) | 3.92 | 3.96 | 3.95 | .88 | .38 | .09 | .01 | .18 | .36 | .49 | 1.42 | 2.09 | 17.73 |