Harper, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Harper, a city in Keokuk County, Iowa.
Tonight
63°F
Chance Showers And Thunderstorms then Showers And Thunderstorms Likely
A chance of rain showers before 10pm, then a chance of showers and thunderstorms between 10pm and 11pm, then showers and thunderstorms likely between 11pm and 1am, then showers and thunderstorms. Some of the storms could produce heavy rain. Mostly cloudy. Low around 63, with temperatures rising to around 67 overnight. North wind 5 to 10 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.
7-day forecast for Harper
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 63°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph N | 86% |
| Sunday | 66°F | Showers And Thunderstorms Likely | 10 to 15 mph N | 60% |
| Sunday Night | 56°F | Showers And Thunderstorms Likely | 15 mph NE | 60% |
| Monday | 60°F | Rain Showers | 15 mph NE | 79% |
| Monday Night | 52°F | Rain Showers Likely | 10 to 15 mph NE | 62% |
| Tuesday | 59°F | Slight Chance Rain Showers | 10 mph NE | 24% |
| Tuesday Night | 48°F | Partly Cloudy | 5 to 10 mph NE | 6% |
| Wednesday | 62°F | Mostly Sunny | 5 to 10 mph NE | 1% |
| Wednesday Night | 51°F | Partly Cloudy | 5 mph NE | 0% |
| Thursday | 65°F | Partly Sunny | 5 mph E | 10% |
| Thursday Night | 56°F | Slight Chance Rain Showers | 0 to 5 mph E | 20% |
| Friday | 69°F | Slight Chance Rain Showers | 5 mph E | 20% |
| Friday Night | 56°F | Mostly Cloudy | 5 mph E | 10% |
| Saturday | 69°F | Partly Sunny then Slight Chance Rain Showers | 5 mph E | 15% |
Forecast source: National Weather Service (api.weather.gov) for Harper (41.364, -92.051). Updated through the day.
Growing snapshot for Harper
Last spring frost
Apr 24
First fall frost
Oct 15
Growing season
172 days
Hardiness zone
5b
More local growing data for Harper: nearby ZIP 52231 weather · frost dates · planting calendar · Iowa frost dates
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Climate data from the nearest NOAA station, Sigourney, Ia (8.9 mi from Harper). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.