Castalia, IA Weather & Growing Conditions
Tonight
50°F
Showers And Thunderstorms
Showers and thunderstorms. Mostly cloudy. Low around 50, with temperatures rising to around 54 overnight. Southeast 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
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 50°F | Showers And Thunderstorms | 10 mph SE | 89% |
| Wednesday | 54°F | Rain Showers Likely | 9 to 15 mph S | 65% |
| 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 NW | 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 | 3% |
| Monday | 59°F | Sunny | 5 to 12 mph SW | 0% |
| Monday Night | 40°F | Mostly Clear | 5 mph W | 1% |
| Tuesday | 58°F | Sunny | 5 mph W | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Castalia, IA
Last spring frost
May 1
First fall frost
Oct 3
Growing season
153 days
Hardiness zone
5a
Explore more for Castalia, IA: full frost dates · planting calendar · Iowa frost dates
Climate data from the nearest NOAA station, Postville, Ia (5.3 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.