Cromwell, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Cromwell, a city in Union County, Iowa.
Tonight
44°F
Rain Showers Likely then Cloudy
Rain showers likely before 10pm. Cloudy, with a low around 44. Northwest wind 13 to 17 mph, with gusts as high as 25 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for Cromwell
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 44°F | Rain Showers Likely then Cloudy | 13 to 17 mph NW | 56% |
| Wednesday | 51°F | Slight Chance Rain Showers | 14 to 17 mph W | 17% |
| Wednesday Night | 41°F | Mostly Cloudy | 12 mph W | 12% |
| Thursday | 52°F | Chance Rain Showers | 12 mph NW | 40% |
| Thursday Night | 39°F | Mostly Cloudy | 9 mph NNW | 11% |
| Friday | 52°F | Partly Sunny | 3 to 8 mph N | 7% |
| Friday Night | 34°F | Mostly Cloudy | 2 mph NE | 0% |
| Saturday | 57°F | Mostly Sunny | 1 to 5 mph WSW | 2% |
| Saturday Night | 37°F | Mostly Clear | 6 mph W | 4% |
| Sunday | 62°F | Sunny | 6 mph W | 5% |
| Sunday Night | 40°F | Mostly Clear | 7 mph SW | 0% |
| Monday | 65°F | Sunny | 7 to 13 mph SW | 0% |
| Monday Night | 42°F | Mostly Clear | 7 mph WNW | 0% |
| Tuesday | 65°F | Mostly Sunny | 7 mph N | 1% |
Forecast source: National Weather Service (api.weather.gov) for Cromwell (41.040, -94.462). Updated through the day.
Growing snapshot for Cromwell
Last spring frost
Apr 28
First fall frost
Oct 11
Growing season
164 days
Hardiness zone
5b
More local growing data for Cromwell: nearby ZIP 50842 weather · frost dates · planting calendar · Iowa frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Creston 2 Sw, Ia (3.6 mi from Cromwell). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.