Marathon, Texas has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 8.6 °C (low) to 25.8 °C (high). Annual precipitation averages 325.4 Millimeters. Marathon is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.1 °C | 16.2 °C | 12.95 mm |
| February | 0.3 °C | 18.8 °C | 7.87 mm |
| March | 4.3 °C | 23 °C | 9.14 mm |
| April | 8.2 °C | 27.3 °C | 13.72 mm |
| May | 12.8 °C | 30.8 °C | 21.08 mm |
| June | 17.2 °C | 33.6 °C | 48.01 mm |
| July | 18 °C | 33.1 °C | 71.37 mm |
| August | 17.7 °C | 33 °C | 50.29 mm |
| September | 14.8 °C | 29.8 °C | 44.96 mm |
| October | 9.2 °C | 26.3 °C | 27.69 mm |
| November | 2.7 °C | 20.8 °C | 9.91 mm |
| December | -0.8 °C | 16.8 °C | 8.38 mm |
| Annual | 8.6 °C | 25.8 °C | 325.37 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |