Bath, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32.2 °F (low) to 54.9 °F (high). Annual precipitation averages 39.1 Inches. Bath is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.7 °F | 27.4 °F | 2.3 in. |
| February | 7.1 °F | 30.8 °F | 2.06 in. |
| March | 17.2 °F | 40.0 °F | 2.36 in. |
| April | 29.7 °F | 53.5 °F | 2.99 in. |
| May | 41.5 °F | 66.9 °F | 3.58 in. |
| June | 50.8 °F | 75.1 °F | 3.99 in. |
| July | 56.0 °F | 80.0 °F | 4.14 in. |
| August | 54.0 °F | 78.5 °F | 3.95 in. |
| September | 46.6 °F | 71.1 °F | 3.59 in. |
| October | 35.5 °F | 57.4 °F | 4.2 in. |
| November | 26.0 °F | 44.6 °F | 2.82 in. |
| December | 15.0 °F | 33.0 °F | 3.08 in. |
| Annual | 32.2 °F | 54.9 °F | 39.06 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |