Newcastle, WY Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Newcastle, a city in Weston County, Wyoming.
Overnight
28°F
Mostly Clear
Mostly clear. Low around 28, with temperatures rising to around 34 overnight. North wind around 6 mph.
7-day forecast for Newcastle
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 28°F | Mostly Clear | 6 mph N | 0% |
| Wednesday | 53°F | Mostly Sunny | 7 mph N | 0% |
| Wednesday Night | 30°F | Partly Cloudy | 2 to 6 mph N | 0% |
| Thursday | 55°F | Mostly Sunny | 1 to 6 mph S | 0% |
| Thursday Night | 34°F | Partly Cloudy | 1 to 6 mph E | 0% |
| Friday | 53°F | Mostly Sunny | 2 to 6 mph NW | 0% |
| Friday Night | 32°F | Mostly Clear | 2 mph E | 0% |
| Saturday | 55°F | Sunny | 1 to 9 mph NW | 0% |
| Saturday Night | 33°F | Mostly Clear | 3 mph E | 0% |
| Sunday | 61°F | Sunny | 3 mph SE | 0% |
| Sunday Night | 38°F | Mostly Clear | 2 mph NE | 0% |
| Monday | 59°F | Sunny | 3 mph NW | 0% |
| Monday Night | 38°F | Partly Cloudy | 3 mph E | 0% |
| Tuesday | 58°F | Mostly Sunny | 3 mph SE | 0% |
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 Nov 4, 2026.