Rock Island, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.9 °C (low) to 22.8 °C (high). Annual precipitation averages 1260.6 Millimeters. Rock Island is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.1 °C | 10.5 °C | 80.26 mm |
| February | 0.1 °C | 13.1 °C | 73.66 mm |
| March | 4.4 °C | 17.8 °C | 109.22 mm |
| April | 9.2 °C | 22.7 °C | 126.24 mm |
| May | 14.7 °C | 26.7 °C | 152.91 mm |
| June | 19.6 °C | 31.3 °C | 109.98 mm |
| July | 21.6 °C | 34.1 °C | 92.71 mm |
| August | 20.8 °C | 33.9 °C | 88.65 mm |
| September | 16.6 °C | 30 °C | 109.98 mm |
| October | 9.8 °C | 24 °C | 105.41 mm |
| November | 4 °C | 17.4 °C | 115.32 mm |
| December | -0.4 °C | 11.9 °C | 96.27 mm |
| Annual | 9.9 °C | 22.8 °C | 1260.61 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |