Metropolis, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.7 °C (low) to 19.9 °C (high). Annual precipitation averages 1299 Millimeters. Metropolis is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.2 °C | 6.2 °C | 106.43 mm |
| February | -1.5 °C | 8.7 °C | 89.41 mm |
| March | 2.9 °C | 14.2 °C | 121.16 mm |
| April | 8.3 °C | 20.6 °C | 130.05 mm |
| May | 14 °C | 25.3 °C | 134.87 mm |
| June | 18.8 °C | 29.8 °C | 121.16 mm |
| July | 20.7 °C | 31.6 °C | 101.85 mm |
| August | 19.4 °C | 30.9 °C | 77.22 mm |
| September | 15.1 °C | 27.7 °C | 91.19 mm |
| October | 8.6 °C | 21.7 °C | 99.06 mm |
| November | 2.8 °C | 14.2 °C | 109.73 mm |
| December | -1.2 °C | 8.2 °C | 116.84 mm |
| Annual | 8.7 °C | 19.9 °C | 1298.97 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |