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
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| 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.