Flanders, New Jersey has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.2 °C (low) to 16 °C (high). Annual precipitation averages 1319.8 Millimeters. Flanders is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.7 °C | 2.6 °C | 97.28 mm |
| February | -6.1 °C | 3.9 °C | 79.76 mm |
| March | -2.1 °C | 8.5 °C | 109.22 mm |
| April | 3.9 °C | 15.7 °C | 103.38 mm |
| May | 9.4 °C | 21.2 °C | 104.9 mm |
| June | 14.8 °C | 25.9 °C | 133.35 mm |
| July | 17.4 °C | 28.7 °C | 118.36 mm |
| August | 16.6 °C | 27.7 °C | 123.44 mm |
| September | 12.3 °C | 23.8 °C | 124.21 mm |
| October | 5.9 °C | 17.3 °C | 116.84 mm |
| November | 0.7 °C | 11.1 °C | 92.71 mm |
| December | -3.2 °C | 5.4 °C | 116.33 mm |
| Annual | 5.2 °C | 16 °C | 1319.78 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |