Thornburg, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Thornburg, a city in Keokuk County, Iowa.
Overnight
63°F
Partly Cloudy
Partly cloudy. Low around 63, with temperatures rising to around 65 overnight. South wind around 5 mph.
7-day forecast for Thornburg
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 63°F | Partly Cloudy | 5 mph S | 0% |
| Tuesday | 84°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 to 10 mph W | 21% |
| Tuesday Night | 64°F | Showers And Thunderstorms Likely | 5 to 10 mph N | 84% |
| Wednesday | 76°F | Showers And Thunderstorms Likely then Chance Showers And Thunderstorms | 5 mph NE | 76% |
| Wednesday Night | 58°F | Chance Showers And Thunderstorms | 5 mph NE | 48% |
| Thursday | 81°F | Slight Chance Rain Showers then Sunny | 5 mph NE | 21% |
| Thursday Night | 60°F | Mostly Clear | 0 to 5 mph E | 2% |
| Friday | 84°F | Sunny | 0 to 5 mph SE | 5% |
| Friday Night | 65°F | Slight Chance Showers And Thunderstorms | 5 mph S | 16% |
| Saturday | 88°F | Sunny then Slight Chance Rain Showers | 5 to 10 mph S | 15% |
| Saturday Night | 71°F | Slight Chance Rain Showers then Mostly Clear | 10 mph S | 15% |
| Sunday | 89°F | Mostly Sunny | 10 mph S | 13% |
| Sunday Night | 69°F | Slight Chance Showers And Thunderstorms | 10 mph S | 32% |
| Monday | 89°F | Chance Showers And Thunderstorms then Slight Chance Showers And Thunderstorms | 10 to 15 mph S | 32% |
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
Delta
Gibson
Harper
Hayesville
Hedrick
Keswick
Kinross
Martinsburg
Ollie
Richland
Sigourney
South English
Webster
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 Aug 4, 2026.