Johnson, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.6 °C (low) to 22.5 °C (high). Annual precipitation averages 996.5 Millimeters. Johnson 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. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.6 °C | 10.3 °C | 39.12 mm |
| February | -0.6 °C | 12.7 °C | 46.74 mm |
| March | 4.2 °C | 17.6 °C | 73.41 mm |
| April | 9 °C | 22.6 °C | 97.79 mm |
| May | 14.4 °C | 26.3 °C | 135.64 mm |
| June | 19.4 °C | 30.9 °C | 129.79 mm |
| July | 21.6 °C | 34 °C | 88.9 mm |
| August | 20.8 °C | 33.9 °C | 83.57 mm |
| September | 16.3 °C | 29.6 °C | 97.79 mm |
| October | 9.9 °C | 23.7 °C | 92.71 mm |
| November | 3.9 °C | 17.1 °C | 58.42 mm |
| December | -0.9 °C | 11.2 °C | 52.58 mm |
| Annual | 9.6 °C | 22.5 °C | 996.46 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| 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 7a : -17.8°C to -15°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |