Altona, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Altona, a community in Boulder County, Colorado.
Today
76°F
Patchy Smoke
Patchy smoke and a slight chance of rain showers. Mostly sunny. High near 76, with temperatures falling to around 73 in the afternoon. East wind around 7 mph. Chance of precipitation is 20%.
7-day forecast for Altona
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 76°F | Patchy Smoke | 7 mph E | 18% |
| Tonight | 55°F | Patchy Smoke | 2 to 7 mph NNE | 11% |
| Wednesday | 84°F | Patchy Smoke | 2 to 7 mph NE | 2% |
| Wednesday Night | 58°F | Mostly Clear | 2 to 6 mph SSE | 1% |
| Thursday | 93°F | Sunny | 1 to 6 mph N | 1% |
| Thursday Night | 61°F | Clear | 3 to 7 mph NW | 1% |
| Friday | 95°F | Sunny | 1 to 7 mph SE | 0% |
| Friday Night | 64°F | Mostly Clear | 3 to 8 mph NW | 0% |
| Saturday | 97°F | Sunny | 2 to 8 mph N | 5% |
| Saturday Night | 66°F | Partly Cloudy | 5 to 8 mph W | 1% |
| Sunday | 96°F | Sunny | 5 mph N | 9% |
| Sunday Night | 68°F | Partly Cloudy | 5 to 8 mph WNW | 6% |
| Monday | 94°F | Mostly Sunny then Chance Showers And Thunderstorms | 7 mph NNW | 34% |
| Monday Night | 66°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 7 mph WSW | 19% |
Forecast source: National Weather Service (api.weather.gov) for Altona (40.122, -105.296). Updated through the day.
Growing snapshot for Altona
Last spring frost
May 6
First fall frost
Oct 5
Growing season
151 days
Hardiness zone
6a
More local growing data for Altona: nearby ZIP 80304 weather · frost dates · planting calendar · Colorado frost dates
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Climate data from the nearest NOAA station, Boulder, Co (3.8 mi from Altona). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.