Thornburg, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Thornburg, a city in Keokuk County, Iowa.
This Afternoon
83°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Partly sunny, with a high near 83. West wind around 5 mph. Chance of precipitation is 30%.
7-day forecast for Thornburg
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 83°F | Chance Showers And Thunderstorms | 5 mph W | 32% |
| Tonight | 63°F | Showers And Thunderstorms Likely | 5 to 10 mph NW | 84% |
| Sunday | 66°F | Chance Rain Showers | 10 to 15 mph NE | 51% |
| Sunday Night | 56°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 58% |
| Monday | 60°F | Rain Showers | 10 to 15 mph NE | 80% |
| Monday Night | 51°F | Rain Showers Likely | 10 to 15 mph NE | 64% |
| Tuesday | 59°F | Slight Chance Rain Showers | 10 mph NE | 21% |
| Tuesday Night | 47°F | Partly Cloudy | 5 to 10 mph NE | 6% |
| Wednesday | 63°F | Mostly Sunny | 5 mph NE | 1% |
| Wednesday Night | 51°F | Partly Cloudy | 0 to 5 mph E | 1% |
| Thursday | 66°F | Partly Sunny | 0 to 5 mph E | 14% |
| Thursday Night | 56°F | Slight Chance Rain Showers | 0 mph | 20% |
| Friday | 69°F | Slight Chance Rain Showers | 0 to 5 mph E | 20% |
| Friday Night | 57°F | Mostly Cloudy | 5 mph E | 10% |
Forecast source: National Weather Service (api.weather.gov) for Thornburg (41.456, -92.332). Updated through the day.
Growing snapshot for Thornburg
Last spring frost
Apr 24
First fall frost
Oct 15
Growing season
172 days
Hardiness zone
5b
More local growing data for Thornburg: nearby ZIP 50255 weather · frost dates · planting calendar · Iowa frost dates
Nearby towns & communities
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Sigourney
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What Cheer
Climate data from the nearest NOAA station, Sigourney, Ia (9.8 mi from Thornburg). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.