Johnstown, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Johnstown, a town in Weld County, Colorado.
Tonight
33°F
Mostly Clear
Mostly clear, with a low around 33. South wind around 3 mph.
7-day forecast for Johnstown
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 33°F | Mostly Clear | 3 mph S | 0% |
| Wednesday | 56°F | Mostly Sunny | 3 mph NNE | 2% |
| Wednesday Night | 34°F | Mostly Cloudy | 5 mph NW | 2% |
| Thursday | 58°F | Sunny | 3 mph S | 0% |
| Thursday Night | 34°F | Partly Cloudy | 2 mph WSW | 1% |
| Friday | 58°F | Mostly Sunny | 5 mph NE | 5% |
| Friday Night | 33°F | Mostly Clear | 3 mph WSW | 5% |
| Saturday | 60°F | Sunny | 3 mph S | 0% |
| Saturday Night | 32°F | Mostly Clear | 2 mph WSW | 0% |
| Sunday | 65°F | Sunny | 2 mph SSE | 0% |
| Sunday Night | 37°F | Mostly Clear | 3 mph WSW | 0% |
| Monday | 65°F | Sunny | 5 mph SE | 0% |
| Monday Night | 37°F | Partly Cloudy | 3 mph NNW | 0% |
| Tuesday | 64°F | Mostly Sunny | 3 mph SSE | 4% |
Forecast source: National Weather Service (api.weather.gov) for Johnstown (40.307, -104.911). Updated through the day.
Growing snapshot for Johnstown
Last spring frost
May 10
First fall frost
Oct 1
Growing season
142 days
Hardiness zone
5b
More local growing data for Johnstown: nearby ZIP 80534 weather · frost dates · planting calendar · Colorado frost dates
Nearby towns & communities
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Frederick
Garden City
Gilcrest
Greeley
Grover
Hudson
Keenesburg
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La Salle
Mead
Milliken
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Platteville
Raymer (New Raymer)
Severance
Windsor
Climate data from the nearest NOAA station, Loveland 2N, Co (10.5 mi from Johnstown). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.