Castalia, IA Weather & Growing Conditions
This Afternoon
70°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Cloudy. High near 70, with temperatures falling to around 67 in the afternoon. East wind around 5 mph. Chance of precipitation is 30%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 70°F | Chance Showers And Thunderstorms | 5 mph E | 34% |
| Tonight | 57°F | Chance Showers And Thunderstorms | 6 to 10 mph NE | 41% |
| Sunday | 67°F | Slight Chance Rain Showers then Mostly Cloudy | 13 mph NE | 18% |
| Sunday Night | 51°F | Mostly Cloudy then Slight Chance Rain Showers | 10 mph NE | 22% |
| Monday | 60°F | Rain Showers Likely | 10 mph NE | 56% |
| Monday Night | 47°F | Rain Showers Likely | 8 mph NE | 56% |
| Tuesday | 60°F | Chance Rain Showers then Partly Sunny | 8 mph NE | 35% |
| Tuesday Night | 44°F | Partly Cloudy | 5 mph NE | 4% |
| Wednesday | 63°F | Mostly Sunny | 5 mph NE | 1% |
| Wednesday Night | 48°F | Partly Cloudy | 2 mph E | 2% |
| Thursday | 65°F | Partly Sunny | 2 mph E | 12% |
| Thursday Night | 53°F | Mostly Cloudy | 0 mph | 11% |
| Friday | 69°F | Partly Sunny | 2 mph E | 9% |
| Friday Night | 54°F | Mostly Cloudy | 1 mph E | 4% |
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 Sep 20, 2026.