Castalia, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Castalia, a city in Winneshiek County, Iowa.
Tonight
50°F
Showers And Thunderstorms
Showers and thunderstorms. Mostly cloudy. Low around 50, with temperatures rising to around 54 overnight. South wind around 10 mph, with gusts as high as 22 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
7-day forecast for Castalia
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 50°F | Showers And Thunderstorms | 10 mph S | 89% |
| Wednesday | 54°F | Rain Showers Likely | 9 to 15 mph S | 66% |
| Wednesday Night | 44°F | Rain Showers | 15 mph SW | 84% |
| Thursday | 50°F | Rain Showers | 13 mph NW | 77% |
| Thursday Night | 38°F | Mostly Cloudy | 12 mph N | 12% |
| Friday | 47°F | Partly Sunny | 2 to 10 mph N | 2% |
| Friday Night | 30°F | Partly Cloudy | 1 mph N | 1% |
| Saturday | 51°F | Mostly Sunny | 0 to 3 mph W | 1% |
| Saturday Night | 35°F | Partly Cloudy | 1 to 5 mph W | 5% |
| Sunday | 57°F | Sunny | 6 mph W | 10% |
| Sunday Night | 36°F | Mostly Clear | 5 mph SW | 2% |
| Monday | 59°F | Sunny | 5 to 10 mph SW | 0% |
| Monday Night | 40°F | Mostly Clear | 6 mph W | 1% |
| Tuesday | 58°F | Sunny | 5 mph NW | 1% |
Forecast source: National Weather Service (api.weather.gov) for Castalia (43.113, -91.677). Updated through the day.
Growing snapshot for Castalia
Last spring frost
May 1
First fall frost
Oct 3
Growing season
153 days
Hardiness zone
5a
More local growing data for Castalia: nearby ZIP 52133 weather · frost dates · planting calendar · Iowa frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Postville, Ia (5.3 mi from Castalia). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.