Pittsburg, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.8 °C (low) to 19.1 °C (high). Annual precipitation averages 1221.2 Millimeters. Pittsburg 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.4 °C | 5 °C | 92.96 mm |
| February | -2.7 °C | 7.8 °C | 77.98 mm |
| March | 1.9 °C | 13.3 °C | 115.32 mm |
| April | 7.6 °C | 19.7 °C | 138.43 mm |
| May | 13.3 °C | 24.4 °C | 129.29 mm |
| June | 18 °C | 29.1 °C | 113.28 mm |
| July | 19.9 °C | 30.8 °C | 102.62 mm |
| August | 18.6 °C | 30.4 °C | 78.99 mm |
| September | 14.2 °C | 27.2 °C | 80.26 mm |
| October | 7.7 °C | 20.9 °C | 89.15 mm |
| November | 2.1 °C | 13.5 °C | 111.25 mm |
| December | -2.2 °C | 7.3 °C | 91.69 mm |
| Annual | 7.8 °C | 19.1 °C | 1221.22 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |