Union, IA Weather & Growing Conditions
Overnight
46°F
Chance Rain Showers
A chance of rain showers. Cloudy. Low around 46, with temperatures rising to around 49 overnight. West northwest wind around 12 mph. Chance of precipitation is 30%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 46°F | Chance Rain Showers | 12 mph WNW | 33% |
| Wednesday | 52°F | Chance Rain Showers | 12 to 17 mph W | 28% |
| Wednesday Night | 42°F | Cloudy then Slight Chance Rain Showers | 13 mph W | 22% |
| Thursday | 52°F | Rain Showers Likely | 9 to 13 mph NW | 64% |
| Thursday Night | 38°F | Slight Chance Rain Showers then Mostly Cloudy | 6 to 9 mph N | 18% |
| Friday | 51°F | Partly Sunny | 3 to 7 mph N | 3% |
| Friday Night | 31°F | Partly Cloudy | 2 mph NNE | 0% |
| Saturday | 55°F | Mostly Sunny | 0 to 3 mph W | 1% |
| Saturday Night | 35°F | Mostly Clear | 3 mph W | 4% |
| Sunday | 60°F | Sunny | 6 mph WNW | 6% |
| Sunday Night | 37°F | Mostly Clear | 5 mph SW | 2% |
| Monday | 64°F | Sunny | 5 to 12 mph SW | 0% |
| Monday Night | 39°F | Mostly Clear | 5 mph WNW | 0% |
| Tuesday | 62°F | Mostly Sunny | 5 mph NW | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Union, IA
Last spring frost
Apr 27
First fall frost
Oct 10
Growing season
165 days
Hardiness zone
5a
Explore more for Union, IA: full frost dates · planting calendar · Iowa frost dates
Climate data from the nearest NOAA station, Eldora, Ia (9.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.