Shirley, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.1 °C (low) to 16.1 °C (high). Annual precipitation averages 1145.3 Millimeters. Shirley is located in USDA Plant Hardiness Zone 6a. 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 | -7.6 °C | 1.2 °C | 80.77 mm |
| February | -6.2 °C | 3.4 °C | 63.25 mm |
| March | -1.4 °C | 9.3 °C | 89.15 mm |
| April | 4.4 °C | 16.4 °C | 115.57 mm |
| May | 10.6 °C | 22.2 °C | 126.49 mm |
| June | 15.6 °C | 26.9 °C | 135.64 mm |
| July | 17 °C | 28.5 °C | 112.27 mm |
| August | 16 °C | 27.9 °C | 86.61 mm |
| September | 11.8 °C | 25 °C | 83.57 mm |
| October | 5.7 °C | 18.3 °C | 82.55 mm |
| November | 0.1 °C | 10.3 °C | 89.15 mm |
| December | -4.5 °C | 3.8 °C | 80.26 mm |
| Annual | 5.1 °C | 16.1 °C | 1145.28 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |