McLennan, Alberta climate data is summarized below. Average annual temperatures range from 25.8 °F (low) to 44.6 °F (high). Annual precipitation averages 17 Inches. McLennan is located in USDA Plant Hardiness Zone 3a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -27.1 °F | -22.4 °F | 0 in. |
| February | -26.2 °F | -21 °F | 0 in. |
| March | -24.3 °F | -18.3 °F | 0 in. |
| April | -19.6 °F | -13.5 °F | 685.8 in. |
| May | -16.1 °F | -8.6 °F | 1524 in. |
| June | -13.3 °F | -6.6 °F | 2438.4 in. |
| July | -12 °F | -5.3 °F | 2565.4 in. |
| August | -12.8 °F | -5.8 °F | 1574.8 in. |
| September | -15.4 °F | -8.7 °F | 1168.4 in. |
| October | -18.2 °F | -13.4 °F | 1016 in. |
| November | -23.2 °F | -19.5 °F | 0 in. |
| December | -28.3 °F | -23.6 °F | 0 in. |
| Annual | 25.8 °F | 44.6 °F | 17 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 3a : -40°F to -35°F |
| Current Drought Conditions | Normal |