Sulphur, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 49.8 °F (low) to 73.3 °F (high). Annual precipitation averages 40 Inches. Sulphur is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 28.0 °F | 51.9 °F | 1.94 in. |
| February | 31.7 °F | 56.0 °F | 2.06 in. |
| March | 40.4 °F | 64.7 °F | 3.14 in. |
| April | 48.4 °F | 73.0 °F | 3.54 in. |
| May | 58.3 °F | 79.6 °F | 5.36 in. |
| June | 67.4 °F | 88.0 °F | 4.59 in. |
| July | 71.1 °F | 93.3 °F | 3.53 in. |
| August | 69.9 °F | 93.9 °F | 2.76 in. |
| September | 62.3 °F | 86.2 °F | 4.11 in. |
| October | 50.3 °F | 75.4 °F | 3.96 in. |
| November | 39.4 °F | 63.6 °F | 2.44 in. |
| December | 30.4 °F | 53.5 °F | 2.52 in. |
| Annual | 49.8 °F | 73.3 °F | 39.95 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |