| 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: | Dec. 11 - Dec. 20 | |
| Average Last Frost Date: | Feb. 11 - Feb. 20 | |
| 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 92377 - Rialto, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 40 | 42 | 43 | 45 | 50 | 54 | 59 | 60 | 57 | 51 | 44 | 40 | 49 |
| Avg Max Temp (°F) | 63 | 66 | 68 | 73 | 78 | 86 | 93 | 93 | 89 | 80 | 70 | 64 | 77 |
| Avg Precip (In.) | 4.66 | 4.65 | 5.06 | 1.13 | .59 | .14 | .05 | .2 | .4 | .68 | 1.7 | 2.73 | 21.99 |