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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

WhenTempForecastWindPrecip
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.