Clear Lake, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2 °C (low) to 12.9 °C (high). Annual precipitation averages 907.6 Millimeters. Clear Lake 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 | -4.7 °C | 23.62 mm |
| February | -11.8 °C | -2.1 °C | 26.92 mm |
| March | -5 °C | 4.8 °C | 50.55 mm |
| April | 1.6 °C | 13.5 °C | 98.3 mm |
| May | 8.6 °C | 20.3 °C | 132.59 mm |
| June | 14.6 °C | 25.9 °C | 136.91 mm |
| July | 16.4 °C | 27.7 °C | 115.32 mm |
| August | 14.8 °C | 26.4 °C | 97.54 mm |
| September | 9.9 °C | 23 °C | 86.61 mm |
| October | 2.9 °C | 15.6 °C | 62.99 mm |
| November | -3.8 °C | 6.2 °C | 42.93 mm |
| December | -10.2 °C | -1.3 °C | 33.27 mm |
| Annual | 2 °C | 12.9 °C | 907.55 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |