Spiro, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 49.7 °F (low) to 72.9 °F (high). Annual precipitation averages 48.4 Inches. Spiro 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 | 28.1 °F | 50.7 °F | 3.12 in. |
| February | 31.8 °F | 55.2 °F | 2.87 in. |
| March | 39.9 °F | 63.7 °F | 4.31 in. |
| April | 48.3 °F | 72.8 °F | 4.84 in. |
| May | 58.5 °F | 79.8 °F | 5.77 in. |
| June | 67.5 °F | 88.4 °F | 4.26 in. |
| July | 71.2 °F | 93.3 °F | 3.68 in. |
| August | 69.7 °F | 93.1 °F | 2.88 in. |
| September | 62.0 °F | 86.1 °F | 4.3 in. |
| October | 49.5 °F | 75.2 °F | 4.04 in. |
| November | 39.0 °F | 63.4 °F | 4.58 in. |
| December | 30.9 °F | 52.9 °F | 3.76 in. |
| Annual | 49.7 °F | 72.9 °F | 48.41 in. |
| 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 : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |