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Thornton, IA Weather & Growing Conditions

This Afternoon
69°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Mostly cloudy. High near 69, with temperatures falling to around 64 in the afternoon. North wind 5 to 8 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.

7-day forecast

WhenTempForecastWindPrecip
This Afternoon 69°F Chance Showers And Thunderstorms 5 to 8 mph N 35%
Tonight 57°F Slight Chance Rain Showers then Slight Chance Drizzle 7 to 12 mph NNE 17%
Sunday 66°F Slight Chance Drizzle 15 mph NE 24%
Sunday Night 50°F Slight Chance Drizzle then Chance Rain Showers 12 mph ENE 44%
Monday 58°F Rain Showers Likely 9 to 13 mph NE 72%
Monday Night 46°F Rain Showers Likely 5 to 9 mph NE 72%
Tuesday 60°F Partly Sunny 5 to 8 mph ENE 13%
Tuesday Night 44°F Partly Cloudy 2 to 6 mph E 1%
Wednesday 64°F Mostly Sunny 5 mph E 1%
Wednesday Night 48°F Partly Cloudy 3 mph ESE 9%
Thursday 66°F Slight Chance Rain Showers 5 mph SE 23%
Thursday Night 53°F Slight Chance Rain Showers 3 mph SE 21%
Friday 70°F Slight Chance Rain Showers then Mostly Cloudy 1 to 5 mph ESE 17%
Friday Night 55°F Mostly Cloudy 3 mph SE 10%

Forecast source: National Weather Service (api.weather.gov). Updated through the day.

Growing snapshot for Thornton, IA

Last spring frost
May 3
First fall frost
Oct 1
Growing season
150 days
Hardiness zone
5a

Explore more for Thornton, IA: full frost dates · planting calendar · Iowa frost dates

Climate data from the nearest NOAA station, Mason City Muni Ap, Ia (15.3 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.