Lester, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 1.8 °C (low) to 13.7 °C (high). Annual precipitation averages 736.9 Millimeters. Lester is located in USDA Plant Hardiness Zone 5a. 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 | -14 °C | -3.7 °C | 16.26 mm |
| February | -11.6 °C | -1 °C | 20.57 mm |
| March | -5.2 °C | 6.1 °C | 38.1 mm |
| April | 1.2 °C | 14.2 °C | 75.18 mm |
| May | 8.2 °C | 20.9 °C | 96.27 mm |
| June | 14.6 °C | 26.7 °C | 120.4 mm |
| July | 16.4 °C | 28.7 °C | 86.36 mm |
| August | 14.9 °C | 27.4 °C | 84.33 mm |
| September | 9.9 °C | 23.7 °C | 80.52 mm |
| October | 2.6 °C | 15.9 °C | 59.44 mm |
| November | -4.7 °C | 6.7 °C | 35.56 mm |
| December | -10.9 °C | -1.1 °C | 23.88 mm |
| Annual | 1.8 °C | 13.7 °C | 736.87 mm |
| 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |