Stephenville, Newfoundland and Labrador climate data is summarized below. Average annual temperatures range from 1.6 °C (low) to 6.9 °C (high). Annual precipitation averages 853 Millimeters. 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 | -8.38 °C | -3.1 °C | 31 mm |
| February | -9.27 °C | -3.7 °C | 22 mm |
| March | -7.54 °C | -2.06 °C | 39 mm |
| April | -2.51 °C | 2.46 °C | 54 mm |
| May | 2.74 °C | 8.5 °C | 71 mm |
| June | 7.58 °C | 13.79 °C | 59 mm |
| July | 12.22 °C | 18.59 °C | 82 mm |
| August | 13.32 °C | 19.29 °C | 102 mm |
| September | 9.85 °C | 15.18 °C | 112 mm |
| October | 5.21 °C | 9.6 °C | 105 mm |
| November | 0.54 °C | 4.73 °C | 106 mm |
| December | -4.55 °C | -0.06 °C | 70 mm |
| Annual | 1.6 °C | 6.9 °C | 853 mm |
| 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 : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |