Stephenville, Newfoundland and Labrador climate data is summarized below. Average annual temperatures range from 34.9 °F (low) to 44.5 °F (high). Annual precipitation averages 33.6 Inches. Stephenville 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 Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -22.4 °F | -19.5 °F | 787.4 in. |
| February | -22.9 °F | -19.8 °F | 558.8 in. |
| March | -22 °F | -18.9 °F | 990.6 in. |
| April | -19.2 °F | -16.4 °F | 1371.6 in. |
| May | -16.3 °F | -13.1 °F | 1803.4 in. |
| June | -13.6 °F | -10.1 °F | 1498.6 in. |
| July | -11 °F | -7.5 °F | 2082.8 in. |
| August | -10.4 °F | -7.1 °F | 2590.8 in. |
| September | -12.3 °F | -9.3 °F | 2844.8 in. |
| October | -14.9 °F | -12.4 °F | 2667 in. |
| November | -17.5 °F | -15.2 °F | 2692.4 in. |
| December | -20.3 °F | -17.8 °F | 1778 in. |
| Annual | 34.9 °F | 44.5 °F | 33.6 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |