Cromwell, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Cromwell, a city in Union County, Iowa.
Today
84°F
Partly Sunny then Chance Showers And Thunderstorms
A chance of showers and thunderstorms after 2pm. Partly sunny. High near 84, with temperatures falling to around 82 in the afternoon. Southwest wind 5 to 9 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 |
|---|---|---|---|---|
| Today | 84°F | Partly Sunny then Chance Showers And Thunderstorms | 5 to 9 mph SW | 39% |
| Tonight | 63°F | Showers And Thunderstorms | 12 mph NNE | 83% |
| Wednesday | 73°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 9 mph NE | 69% |
| Wednesday Night | 58°F | Chance Showers And Thunderstorms | 3 to 9 mph NE | 34% |
| Thursday | 81°F | Mostly Sunny | 3 mph E | 6% |
| Thursday Night | 62°F | Mostly Clear | 3 mph SE | 6% |
| Friday | 85°F | Sunny | 7 mph S | 6% |
| Friday Night | 67°F | Mostly Clear | 6 mph S | 9% |
| Saturday | 89°F | Sunny | 5 to 12 mph S | 3% |
| Saturday Night | 72°F | Mostly Clear | 12 to 15 mph S | 9% |
| Sunday | 91°F | Mostly Sunny | 14 mph S | 9% |
| Sunday Night | 71°F | Slight Chance Showers And Thunderstorms | 14 mph S | 17% |
| Monday | 91°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 13 to 16 mph SSW | 17% |
| Monday Night | 72°F | Slight Chance Showers And Thunderstorms | 13 to 16 mph SSE | 24% |
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 Aug 4, 2026.