Altona, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Altona, a community in Boulder County, Colorado.
This Afternoon
54°F
Sunny
Sunny. High near 54, with temperatures falling to around 48 in the afternoon. East wind around 3 mph.
7-day forecast for Altona
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 54°F | Sunny | 3 mph E | 0% |
| Tonight | 34°F | Mostly Clear | 2 mph WSW | 0% |
| Wednesday | 54°F | Partly Sunny | 0 to 5 mph NE | 12% |
| Wednesday Night | 32°F | Mostly Cloudy | 2 mph NW | 12% |
| Thursday | 57°F | Sunny | 0 to 6 mph S | 0% |
| Thursday Night | 36°F | Partly Cloudy | 0 to 3 mph WSW | 1% |
| Friday | 56°F | Mostly Sunny | 3 mph S | 13% |
| Friday Night | 34°F | Mostly Clear | 2 to 7 mph WSW | 13% |
| Saturday | 59°F | Sunny | 0 to 9 mph SSW | 1% |
| Saturday Night | 34°F | Mostly Clear | 1 to 5 mph W | 1% |
| Sunday | 66°F | Sunny | 0 to 7 mph SSW | 0% |
| Sunday Night | 42°F | Mostly Clear | 5 to 13 mph W | 0% |
| Monday | 66°F | Mostly Sunny | 0 to 9 mph ESE | 0% |
| Monday Night | 41°F | Partly Cloudy | 0 to 5 mph W | 0% |
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 Nov 4, 2026.