Johnstown, WY Weather & Growing Conditions
Overnight
50°F
Isolated Showers And Thunderstorms
Isolated showers and thunderstorms before 3am, then patchy fog. Mostly cloudy, with a low around 50. North northwest wind around 6 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 50°F | Isolated Showers And Thunderstorms | 6 mph NNW | 20% |
| Saturday | 67°F | Scattered Showers And Thunderstorms | 3 to 8 mph N | 46% |
| Saturday Night | 44°F | Scattered Showers And Thunderstorms then Showers And Thunderstorms Likely | 3 to 8 mph WNW | 70% |
| Sunday | 63°F | Chance Showers And Thunderstorms | 2 to 7 mph WNW | 28% |
| Sunday Night | 43°F | Partly Cloudy | 2 to 7 mph SSW | 7% |
| Monday | 68°F | Sunny | 3 to 7 mph S | 1% |
| Monday Night | 45°F | Mostly Clear | 5 to 8 mph N | 1% |
| Tuesday | 73°F | Mostly Sunny | 7 mph NNE | 4% |
| Tuesday Night | 48°F | Slight Chance Showers And Thunderstorms | 5 to 9 mph NNW | 22% |
| Wednesday | 75°F | Sunny | 5 to 9 mph N | 5% |
| Wednesday Night | 48°F | Mostly Clear | 9 mph W | 4% |
| Thursday | 77°F | Sunny | 5 to 8 mph NNE | 3% |
| Thursday Night | 48°F | Partly Cloudy | 9 mph WSW | 6% |
| Friday | 78°F | Mostly Sunny | 7 mph SW | 4% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Johnstown, WY
Last spring frost
May 21
First fall frost
Sep 20
Growing season
119 days
Hardiness zone
5a
Explore more for Johnstown, WY: full frost dates · planting calendar · Wyoming frost dates
Climate data from the nearest NOAA station, Diversion Dam, Wy (4.5 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.