Jamestown, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Jamestown, a town in Boulder County, Colorado.
This Afternoon
72°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms before 3pm, then showers and thunderstorms likely. Mostly cloudy. High near 72, with temperatures falling to around 58 in the afternoon. South wind around 5 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for Jamestown
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 72°F | Chance Showers And Thunderstorms | 5 mph S | 58% |
| Tonight | 49°F | Chance Showers And Thunderstorms then Partly Cloudy | 6 mph W | 29% |
| Saturday | 66°F | Slight Chance Rain Showers then Chance Showers And Thunderstorms | 2 to 6 mph SW | 71% |
| Saturday Night | 45°F | Chance Showers And Thunderstorms then Slight Chance Showers And Thunderstorms | 3 mph W | 39% |
| Sunday | 60°F | Chance Showers And Thunderstorms | 5 mph N | 34% |
| Sunday Night | 44°F | Chance Rain Showers then Partly Cloudy | 2 mph NW | 26% |
| Monday | 61°F | Sunny | 1 to 8 mph S | 5% |
| Monday Night | 47°F | Mostly Clear | 2 mph SW | 7% |
| Tuesday | 66°F | Mostly Sunny then Chance Showers And Thunderstorms | 0 to 3 mph S | 36% |
| Tuesday Night | 49°F | Slight Chance Showers And Thunderstorms then Mostly Cloudy | 2 mph S | 23% |
| Wednesday | 67°F | Partly Sunny then Chance Showers And Thunderstorms | 3 mph N | 37% |
| Wednesday Night | 48°F | Slight Chance Rain Showers then Mostly Cloudy | 2 mph SW | 19% |
| Thursday | 67°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 mph SSE | 24% |
| Thursday Night | 50°F | Chance Rain Showers then Mostly Cloudy | 2 mph SSW | 25% |
Forecast source: National Weather Service (api.weather.gov) for Jamestown (40.123, -105.393). Updated through the day.
Growing snapshot for Jamestown
Last spring frost
Jun 21
First fall frost
Sep 2
Growing season
71 days
Hardiness zone
5b
More local growing data for Jamestown: nearby ZIP 80455 weather · frost dates · planting calendar · Colorado frost dates
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Climate data from the nearest NOAA station, Boulder 14 W, Co (8.6 mi from Jamestown). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 18, 2026.