Califon, New Jersey has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.1 °C (low) to 16 °C (high). Annual precipitation averages 1334 Millimeters. Califon is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.6 °C | 2.8 °C | 95 mm |
| February | -5.9 °C | 4.2 °C | 77.22 mm |
| March | -2.2 °C | 8.8 °C | 108.46 mm |
| April | 3.8 °C | 15.9 °C | 105.92 mm |
| May | 9.3 °C | 21.2 °C | 110.74 mm |
| June | 14.6 °C | 25.9 °C | 129.54 mm |
| July | 17 °C | 28.4 °C | 131.57 mm |
| August | 16.3 °C | 27.4 °C | 124.97 mm |
| September | 12.2 °C | 23.7 °C | 124.46 mm |
| October | 5.9 °C | 17.4 °C | 114.55 mm |
| November | 0.6 °C | 11.2 °C | 92.96 mm |
| December | -3.4 °C | 5.4 °C | 118.62 mm |
| Annual | 5.1 °C | 16 °C | 1334.01 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |