Newcastle, WY Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Newcastle, a city in Weston County, Wyoming.
Overnight
49°F
Areas Of Smoke
Areas of smoke. Mostly clear, with a low around 49. Northeast wind around 3 mph.
7-day forecast for Newcastle
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 49°F | Areas Of Smoke | 3 mph NE | 1% |
| Tuesday | 72°F | Areas Of Smoke | 5 mph SE | 5% |
| Tuesday Night | 50°F | Partly Cloudy then Slight Chance Rain Showers | 3 to 7 mph E | 18% |
| Wednesday | 80°F | Sunny | 5 mph S | 3% |
| Wednesday Night | 55°F | Mostly Clear | 6 mph E | 0% |
| Thursday | 90°F | Sunny | 1 to 6 mph NW | 0% |
| Thursday Night | 61°F | Mostly Clear | 3 to 8 mph NE | 0% |
| Friday | 93°F | Sunny | 2 to 7 mph S | 1% |
| Friday Night | 66°F | Mostly Clear | 5 to 12 mph E | 0% |
| Saturday | 96°F | Sunny | 3 to 9 mph NW | 0% |
| Saturday Night | 64°F | Mostly Clear | 5 to 12 mph NE | 1% |
| Sunday | 95°F | Sunny | 5 to 13 mph SE | 2% |
| Sunday Night | 65°F | Partly Cloudy | 3 to 13 mph E | 11% |
| Monday | 93°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 3 to 13 mph SE | 16% |
Forecast source: National Weather Service (api.weather.gov) for Newcastle (43.850, -104.196). Updated through the day.
Growing snapshot for Newcastle
Last spring frost
May 20
First fall frost
Sep 23
Growing season
123 days
Hardiness zone
4b
More local growing data for Newcastle: nearby ZIP 82723 weather · frost dates · planting calendar · Wyoming frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Upton, Wy (11.4 mi from Newcastle). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.