Brighton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 16 °C (high). Annual precipitation averages 970.5 Millimeters. Brighton 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 | -9.9 °C | -0.5 °C | 35.05 mm |
| February | -7.9 °C | 2.1 °C | 41.4 mm |
| March | -2 °C | 9.3 °C | 59.94 mm |
| April | 4.2 °C | 16.9 °C | 92.96 mm |
| May | 10.8 °C | 22.7 °C | 132.33 mm |
| June | 16.3 °C | 27.8 °C | 128.27 mm |
| July | 18.3 °C | 29.7 °C | 103.89 mm |
| August | 16.9 °C | 28.8 °C | 111.25 mm |
| September | 11.9 °C | 25.3 °C | 86.36 mm |
| October | 5.4 °C | 18.2 °C | 76.2 mm |
| November | -0.9 °C | 9.6 °C | 57.91 mm |
| December | -6.7 °C | 2.4 °C | 44.96 mm |
| Annual | 4.7 °C | 16 °C | 970.52 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 |