Hallett, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.3 °C (low) to 22.1 °C (high). Annual precipitation averages 1019.8 Millimeters. Hallett is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.3 °C | 9.5 °C | 39.62 mm |
| February | -1.4 °C | 12 °C | 42.93 mm |
| March | 3.6 °C | 17.2 °C | 77.98 mm |
| April | 8.7 °C | 22.5 °C | 108.2 mm |
| May | 14.4 °C | 26.3 °C | 147.57 mm |
| June | 19.3 °C | 30.7 °C | 116.84 mm |
| July | 21.7 °C | 33.6 °C | 96.27 mm |
| August | 20.8 °C | 33.7 °C | 91.95 mm |
| September | 16.2 °C | 29.2 °C | 97.03 mm |
| October | 9.6 °C | 23.3 °C | 93.22 mm |
| November | 3.2 °C | 16.6 °C | 60.45 mm |
| December | -1.7 °C | 10.3 °C | 47.75 mm |
| Annual | 9.3 °C | 22.1 °C | 1019.81 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°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 |