Castalia, IA Weather & Growing Conditions
Today
76°F
Mostly Cloudy then Scattered Showers And Thunderstorms
Scattered rain showers between noon and 4pm, then scattered showers and thunderstorms between 4pm and 5pm, then scattered showers and thunderstorms. Mostly cloudy. High near 76, with temperatures falling to around 73 in the afternoon. Northwest wind 5 to 8 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 76°F | Mostly Cloudy then Scattered Showers And Thunderstorms | 5 to 8 mph NW | 52% |
| Tonight | 60°F | Chance Showers And Thunderstorms then Scattered Showers And Thunderstorms | 5 mph NW | 64% |
| Wednesday | 73°F | Slight Chance Rain Showers then Partly Sunny | 3 mph N | 16% |
| Wednesday Night | 54°F | Mostly Clear | 2 mph NW | 2% |
| Thursday | 77°F | Sunny | 2 mph SW | 1% |
| Thursday Night | 58°F | Mostly Clear | 2 mph S | 0% |
| Friday | 80°F | Sunny | 2 to 8 mph S | 5% |
| Friday Night | 63°F | Mostly Clear | 6 mph S | 10% |
| Saturday | 82°F | Mostly Sunny | 6 mph S | 9% |
| Saturday Night | 67°F | Slight Chance Showers And Thunderstorms | 7 mph S | 32% |
| Sunday | 83°F | Chance Showers And Thunderstorms | 8 mph S | 32% |
| Sunday Night | 66°F | Chance Showers And Thunderstorms | 6 mph S | 41% |
| Monday | 81°F | Chance Showers And Thunderstorms | 7 mph S | 41% |
| Monday Night | 66°F | Chance Showers And Thunderstorms | 7 mph NE | 34% |
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 Aug 4, 2026.