McLean, Nebraska has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.2 °F (low) to 60.9 °F (high). Annual precipitation averages 28.1 Inches. McLean 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 | 11.4 °F | 33.3 °F | 0.56 in. |
| February | 16.0 °F | 38.5 °F | 0.77 in. |
| March | 25.2 °F | 50.3 °F | 1.48 in. |
| April | 35.4 °F | 60.4 °F | 3.03 in. |
| May | 47.4 °F | 71.8 °F | 4.24 in. |
| June | 58.6 °F | 81.7 °F | 4.2 in. |
| July | 63.2 °F | 85.8 °F | 3.0 in. |
| August | 60.9 °F | 83.6 °F | 3.58 in. |
| September | 51.4 °F | 77.0 °F | 2.81 in. |
| October | 37.8 °F | 63.9 °F | 2.42 in. |
| November | 24.3 °F | 48.9 °F | 1.15 in. |
| December | 14.5 °F | 35.6 °F | 0.82 in. |
| Annual | 37.2 °F | 60.9 °F | 28.06 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 |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |