Smiths Falls, Ontario climate data is summarized below. Average annual temperatures range from 34.9 °F (low) to 53.9 °F (high). Annual precipitation averages 32.7 Inches. Smiths Falls 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 | -25 °F | -19.9 °F | 254 in. |
| February | -25.2 °F | -19.6 °F | 203.2 in. |
| March | -21.7 °F | -15.8 °F | 939.8 in. |
| April | -17.2 °F | -11 °F | 2082.8 in. |
| May | -13.7 °F | -6.8 °F | 2387.6 in. |
| June | -10.8 °F | -4.5 °F | 3225.8 in. |
| July | -9.5 °F | -3 °F | 3556 in. |
| August | -10 °F | -3.5 °F | 2514.6 in. |
| September | -12.6 °F | -5.9 °F | 2108.2 in. |
| October | -15.5 °F | -10 °F | 1905 in. |
| November | -18.8 °F | -13.9 °F | 1168.4 in. |
| December | -22.5 °F | -18.4 °F | 762 in. |
| Annual | 34.9 °F | 53.9 °F | 32.71 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 |