New Castle, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for New Castle, a town in Garfield County, Colorado.
This Afternoon
77°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Partly sunny, with a high near 77. West southwest wind around 5 mph. Chance of precipitation is 40%.
7-day forecast for New Castle
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 77°F | Chance Showers And Thunderstorms | 5 mph WSW | 36% |
| Tonight | 49°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph E | 66% |
| Saturday | 75°F | Showers And Thunderstorms Likely then Chance Showers And Thunderstorms | 5 to 10 mph SSE | 64% |
| Saturday Night | 45°F | Slight Chance Showers And Thunderstorms | 0 to 5 mph ENE | 30% |
| Sunday | 74°F | Sunny | 0 to 10 mph WNW | 3% |
| Sunday Night | 43°F | Mostly Clear | 5 mph NNE | 0% |
| Monday | 79°F | Sunny | 0 to 5 mph SSW | 0% |
| Monday Night | 46°F | Mostly Clear | 0 to 5 mph NNE | 2% |
| Tuesday | 79°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 mph S | 13% |
| Tuesday Night | 47°F | Chance Showers And Thunderstorms | 0 to 5 mph SE | 39% |
| Wednesday | 77°F | Slight Chance Rain Showers then Slight Chance Showers And Thunderstorms | 0 to 5 mph SSE | 18% |
| Wednesday Night | 46°F | Partly Cloudy | 0 mph | 8% |
| Thursday | 79°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 0 to 5 mph S | 15% |
| Thursday Night | 49°F | Slight Chance Showers And Thunderstorms | 0 mph | 20% |
Forecast source: National Weather Service (api.weather.gov) for New Castle (39.578, -107.526). Updated through the day.
Growing snapshot for New Castle
Last spring frost
May 23
First fall frost
Sep 25
Growing season
124 days
Hardiness zone
6a
More local growing data for New Castle: nearby ZIP 81647 weather · frost dates · planting calendar · Colorado frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Rifle 3Ene, Co (10.4 mi from New Castle). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.