Johnston, IA Weather & Growing Conditions
Today
52°F
Cloudy
Cloudy. High near 52, with temperatures falling to around 50 in the afternoon. West wind around 15 mph, with gusts as high as 24 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 52°F | Cloudy | 15 mph W | 11% |
| Tonight | 44°F | Cloudy then Chance Rain Showers | 12 mph W | 25% |
| Thursday | 53°F | Chance Rain Showers then Mostly Cloudy | 12 mph NW | 39% |
| Thursday Night | 40°F | Mostly Cloudy | 5 to 9 mph NNW | 6% |
| Friday | 50°F | Partly Sunny | 3 to 7 mph N | 5% |
| Friday Night | 31°F | Partly Cloudy | 2 mph NNE | 2% |
| Saturday | 53°F | Mostly Sunny | 0 to 3 mph SW | 2% |
| Saturday Night | 36°F | Mostly Clear | 3 mph W | 1% |
| Sunday | 60°F | Sunny | 5 mph W | 1% |
| Sunday Night | 38°F | Clear | 5 mph SW | 0% |
| Monday | 65°F | Sunny | 3 to 8 mph SW | 0% |
| Monday Night | 41°F | Mostly Clear | 2 to 6 mph WNW | 0% |
| Tuesday | 64°F | Sunny | 3 mph NNW | 0% |
| Tuesday Night | 43°F | Partly Cloudy | 3 mph ESE | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Johnston, IA
Last spring frost
Apr 19
First fall frost
Oct 18
Growing season
179 days
Hardiness zone
5b
Explore more for Johnston, IA: full frost dates · planting calendar · Iowa frost dates
Climate data from the nearest NOAA station, Des Moines Wsfo-Johnston, Ia (2.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.