New Castle, CO Weather & Growing Conditions
Tonight
49°F
Chance Showers And Thunderstorms then Showers And Thunderstorms Likely
A chance of showers and thunderstorms before midnight, then showers and thunderstorms likely. Mostly cloudy, with a low around 49. East northeast wind 5 to 10 mph. Chance of precipitation is 70%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 49°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph ENE | 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% |
| Friday | 78°F | Chance Showers And Thunderstorms | 0 to 5 mph SSE | 28% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for New Castle, CO
Last spring frost
May 23
First fall frost
Sep 25
Growing season
124 days
Hardiness zone
6a
Explore more for New Castle, CO: full frost dates · planting calendar · Colorado frost dates
Climate data from the nearest NOAA station, Rifle 3Ene, Co (10.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.