Union, IA Weather & Growing Conditions
Overnight
67°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Mostly cloudy, with a low around 67. South southeast wind around 6 mph. Chance of precipitation is 40%. New rainfall amounts between a quarter and half of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 67°F | Chance Showers And Thunderstorms | 6 mph SSE | 41% |
| Saturday | 79°F | Showers And Thunderstorms Likely | 8 mph WSW | 57% |
| Saturday Night | 60°F | Chance Showers And Thunderstorms | 9 mph N | 33% |
| Sunday | 66°F | Chance Rain Showers | 10 to 14 mph NE | 32% |
| Sunday Night | 54°F | Chance Rain Showers | 13 mph ENE | 43% |
| Monday | 62°F | Chance Rain Showers | 13 mph NE | 44% |
| Monday Night | 49°F | Chance Rain Showers | 6 to 10 mph NE | 44% |
| Tuesday | 61°F | Slight Chance Rain Showers then Partly Sunny | 8 mph ENE | 15% |
| Tuesday Night | 45°F | Partly Cloudy | 2 to 6 mph ENE | 2% |
| Wednesday | 66°F | Sunny | 5 mph ENE | 1% |
| Wednesday Night | 50°F | Partly Cloudy | 3 mph E | 5% |
| Thursday | 67°F | Partly Sunny | 3 mph ESE | 13% |
| Thursday Night | 53°F | Mostly Cloudy | 2 mph E | 10% |
| Friday | 69°F | Partly Sunny | 1 to 5 mph ESE | 6% |
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 Sep 19, 2026.