Farnham, Quebec climate data is summarized below. Average annual temperatures range from 36.2 °F (low) to 53.8 °F (high). Annual precipitation averages 19 Inches. Farnham is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -24.8 °F | -19.9 °F | 330.2 in. |
| February | -24.7 °F | -19.6 °F | 330.2 in. |
| March | -21.4 °F | -15.9 °F | 762 in. |
| April | -17 °F | -11 °F | 1524 in. |
| May | -13.2 °F | -6.8 °F | 1346.2 in. |
| June | -10.4 °F | -4.5 °F | 1447.8 in. |
| July | -9 °F | -3 °F | 1879.6 in. |
| August | -9.5 °F | -3.5 °F | 1219.2 in. |
| September | -12.1 °F | -6 °F | 787.4 in. |
| October | -15.1 °F | -10.1 °F | 1193.8 in. |
| November | -18.2 °F | -13.9 °F | 889 in. |
| December | -22.2 °F | -18.2 °F | 533.4 in. |
| Annual | 36.2 °F | 53.8 °F | 18.97 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |