Essex, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.5 °C (low) to 16.8 °C (high). Annual precipitation averages 895.8 Millimeters. Essex is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.4 °C | 0.6 °C | 21.59 mm |
| February | -8.1 °C | 3.4 °C | 28.45 mm |
| March | -2.1 °C | 10.7 °C | 48.51 mm |
| April | 3.8 °C | 17.4 °C | 84.84 mm |
| May | 10.7 °C | 23.1 °C | 146.3 mm |
| June | 16.6 °C | 28.2 °C | 137.41 mm |
| July | 18.7 °C | 30.1 °C | 105.66 mm |
| August | 17.1 °C | 29.3 °C | 92.2 mm |
| September | 11.8 °C | 25.9 °C | 80.26 mm |
| October | 4.8 °C | 19.1 °C | 71.88 mm |
| November | -2 °C | 10.2 °C | 46.23 mm |
| December | -7.4 °C | 3.2 °C | 32.51 mm |
| Annual | 4.5 °C | 16.8 °C | 895.84 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |