Cromwell, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Cromwell, a city in Union County, Iowa.
Overnight
70°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Mostly cloudy, with a low around 70. West southwest wind around 5 mph. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for Cromwell
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 70°F | Chance Showers And Thunderstorms | 5 mph WSW | 36% |
| Saturday | 81°F | Chance Showers And Thunderstorms | 5 to 10 mph WSW | 43% |
| Saturday Night | 62°F | Showers And Thunderstorms Likely | 9 mph N | 56% |
| Sunday | 66°F | Slight Chance Rain Showers then Slight Chance Showers And Thunderstorms | 9 to 13 mph NNE | 43% |
| Sunday Night | 57°F | Chance Showers And Thunderstorms | 12 mph NE | 54% |
| Monday | 60°F | Showers And Thunderstorms Likely | 13 mph NE | 55% |
| Monday Night | 52°F | Chance Rain Showers | 7 to 10 mph NE | 49% |
| Tuesday | 59°F | Partly Sunny | 9 mph ENE | 9% |
| Tuesday Night | 46°F | Partly Cloudy | 3 to 7 mph ENE | 7% |
| Wednesday | 63°F | Mostly Sunny | 5 mph E | 2% |
| Wednesday Night | 51°F | Partly Cloudy | 3 mph E | 8% |
| Thursday | 65°F | Chance Rain Showers | 5 mph ESE | 25% |
| Thursday Night | 56°F | Mostly Cloudy then Slight Chance Rain Showers | 3 mph ESE | 21% |
| Friday | 66°F | Slight Chance Rain Showers | 3 to 7 mph ESE | 21% |
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 Sep 19, 2026.