Johnstown, CO Weather & Growing Conditions
Today
78°F
Patchy Smoke
Patchy smoke. Mostly sunny, with a high near 78. East southeast wind 8 to 12 mph, with gusts as high as 18 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 78°F | Patchy Smoke | 8 to 12 mph ESE | 5% |
| Tonight | 55°F | Patchy Smoke | 6 to 12 mph ENE | 8% |
| Wednesday | 86°F | Patchy Smoke | 6 to 10 mph ENE | 0% |
| Wednesday Night | 57°F | Patchy Smoke then Mostly Clear | 5 to 12 mph NE | 1% |
| Thursday | 95°F | Sunny | 3 to 7 mph NNW | 0% |
| Thursday Night | 60°F | Mostly Clear | 5 to 8 mph N | 1% |
| Friday | 97°F | Sunny | 2 to 7 mph SW | 0% |
| Friday Night | 62°F | Mostly Clear | 8 mph SSW | 0% |
| Saturday | 99°F | Sunny | 2 to 9 mph NE | 2% |
| Saturday Night | 62°F | Partly Cloudy | 5 to 10 mph WNW | 1% |
| Sunday | 98°F | Sunny | 2 to 10 mph N | 6% |
| Sunday Night | 64°F | Partly Cloudy | 5 to 12 mph W | 6% |
| Monday | 97°F | Sunny | 5 to 14 mph NNE | 13% |
| Monday Night | 64°F | Mostly Cloudy | 5 to 16 mph NW | 12% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Johnstown, CO
Last spring frost
May 10
First fall frost
Oct 1
Growing season
142 days
Hardiness zone
5b
Explore more for Johnstown, CO: full frost dates · planting calendar · Colorado frost dates
Climate data from the nearest NOAA station, Loveland 2N, Co (10.5 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.