Newcastle, Wyoming has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 33.2 °F (low) to 58.8 °F (high). Annual precipitation averages 17.3 Inches. Newcastle is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.6 °F | 34.8 °F | 0.49 in. |
| February | 14.1 °F | 37.3 °F | 0.63 in. |
| March | 23.2 °F | 47.7 °F | 0.81 in. |
| April | 30.8 °F | 56.4 °F | 1.75 in. |
| May | 40.9 °F | 65.8 °F | 2.97 in. |
| June | 50.3 °F | 77.0 °F | 2.76 in. |
| July | 57.1 °F | 86.3 °F | 2.42 in. |
| August | 55.0 °F | 85.2 °F | 2.0 in. |
| September | 45.7 °F | 75.0 °F | 1.13 in. |
| October | 33.2 °F | 59.5 °F | 1.26 in. |
| November | 22.0 °F | 45.8 °F | 0.56 in. |
| December | 13.3 °F | 35.0 °F | 0.51 in. |
| Annual | 33.2 °F | 58.8 °F | 17.29 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |