Newcastle, Utah has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.9 °C (low) to 18.5 °C (high). Annual precipitation averages 336.8 Millimeters. Newcastle is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.5 °C | 5.8 °C | 30.99 mm |
| February | -6.7 °C | 8.2 °C | 40.13 mm |
| March | -3.6 °C | 13.2 °C | 41.15 mm |
| April | -1.3 °C | 16.8 °C | 23.37 mm |
| May | 3.1 °C | 22.1 °C | 22.61 mm |
| June | 8.6 °C | 28.7 °C | 11.18 mm |
| July | 13.1 °C | 32.1 °C | 21.08 mm |
| August | 12.3 °C | 30.9 °C | 35.56 mm |
| September | 7.1 °C | 26.9 °C | 31.24 mm |
| October | 0.7 °C | 19.9 °C | 24.38 mm |
| November | -5.2 °C | 12.1 °C | 22.61 mm |
| December | -9.1 °C | 5.7 °C | 32.51 mm |
| Annual | 0.9 °C | 18.5 °C | 336.81 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |