Amboy, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.9 °C (low) to 15.1 °C (high). Annual precipitation averages 966.5 Millimeters. Amboy 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 | -10.5 °C | -1.4 °C | 45.21 mm |
| February | -8.4 °C | 1.1 °C | 44.7 mm |
| March | -2.8 °C | 8.1 °C | 60.96 mm |
| April | 3 °C | 15.7 °C | 88.9 mm |
| May | 9.7 °C | 22 °C | 122.68 mm |
| June | 15.1 °C | 26.9 °C | 132.33 mm |
| July | 16.9 °C | 28.5 °C | 105.41 mm |
| August | 15.7 °C | 27.6 °C | 99.82 mm |
| September | 11.2 °C | 24.4 °C | 86.61 mm |
| October | 4.7 °C | 17.3 °C | 70.36 mm |
| November | -1.3 °C | 8.8 °C | 57.91 mm |
| December | -7.1 °C | 1.6 °C | 51.56 mm |
| Annual | 3.9 °C | 15.1 °C | 966.45 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 |