Forbes, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.1 °C (low) to 11.9 °C (high). Annual precipitation averages 563.1 Millimeters. Forbes is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.5 °C | -6.2 °C | 14.22 mm |
| February | -14.3 °C | -3.7 °C | 15.75 mm |
| March | -7.8 °C | 3.3 °C | 24.38 mm |
| April | -0.7 °C | 12.3 °C | 43.18 mm |
| May | 6.6 °C | 19.6 °C | 78.49 mm |
| June | 12.7 °C | 24.9 °C | 97.03 mm |
| July | 15.1 °C | 27.9 °C | 85.6 mm |
| August | 13.6 °C | 27.3 °C | 64.77 mm |
| September | 8.3 °C | 22.4 °C | 59.18 mm |
| October | 1 °C | 13.8 °C | 46.48 mm |
| November | -6.6 °C | 4.2 °C | 17.78 mm |
| December | -12.8 °C | -3.3 °C | 16.26 mm |
| Annual | -0.1 °C | 11.9 °C | 563.12 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |