Blairstown, New Jersey has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.2 °C (low) to 16.4 °C (high). Annual precipitation averages 1243.3 Millimeters. Blairstown 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 | -7.4 °C | 2.8 °C | 88.14 mm |
| February | -6.7 °C | 4.6 °C | 70.87 mm |
| March | -3.1 °C | 9.2 °C | 99.31 mm |
| April | 2.7 °C | 16.3 °C | 97.03 mm |
| May | 8.5 °C | 21.9 °C | 101.85 mm |
| June | 13.6 °C | 26.2 °C | 123.7 mm |
| July | 16.3 °C | 28.9 °C | 114.05 mm |
| August | 15.3 °C | 27.8 °C | 120.9 mm |
| September | 11.3 °C | 24.4 °C | 119.38 mm |
| October | 4.8 °C | 17.8 °C | 117.09 mm |
| November | -0.8 °C | 11.6 °C | 85.6 mm |
| December | -4.5 °C | 5.7 °C | 105.41 mm |
| Annual | 4.2 °C | 16.4 °C | 1243.33 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |