Palmerston, Ontario climate data is summarized below. Average annual temperatures range from 35.8 °F (low) to 52.3 °F (high). Annual precipitation averages 17.9 Inches. Palmerston is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -23.7 °F | -19.7 °F | 0 in. |
| February | -24.5 °F | -20 °F | 0 in. |
| March | -21.1 °F | -16 °F | 558.8 in. |
| April | -17.5 °F | -11.7 °F | 762 in. |
| May | -13.9 °F | -7.7 °F | 1397 in. |
| June | -11.2 °F | -5.3 °F | 1955.8 in. |
| July | -10 °F | -4 °F | 2286 in. |
| August | -10.2 °F | -4.4 °F | 2159 in. |
| September | -12.3 °F | -6.6 °F | 1066.8 in. |
| October | -15.1 °F | -10.5 °F | 685.8 in. |
| November | -18.3 °F | -14.3 °F | 431.8 in. |
| December | -21.3 °F | -18 °F | 254 in. |
| Annual | 35.8 °F | 52.3 °F | 17.91 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |