Union, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union, a village in Mchenry County, Illinois.
Tonight
61°F
Isolated Rain Showers then Showers And Thunderstorms Likely
Isolated rain showers before 8pm, then showers and thunderstorms likely. Some of the storms could produce heavy rain. Mostly cloudy, with a low around 61. East wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 70%. New rainfall amounts between a half and three quarters of an inch possible.
7-day forecast for Union
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 61°F | Isolated Rain Showers then Showers And Thunderstorms Likely | 10 mph E | 66% |
| Saturday | 76°F | Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph SE | 93% |
| Saturday Night | 62°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 to 10 mph NE | 78% |
| Sunday | 67°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 72% |
| Sunday Night | 54°F | Chance Rain Showers | 10 to 15 mph ENE | 48% |
| Monday | 64°F | Chance Rain Showers | 15 mph ENE | 40% |
| Monday Night | 50°F | Chance Rain Showers | 10 to 15 mph ENE | 40% |
| Tuesday | 62°F | Slight Chance Rain Showers | 10 to 15 mph NE | 19% |
| Tuesday Night | 49°F | Mostly Cloudy | 5 to 10 mph NE | 12% |
| Wednesday | 65°F | Partly Sunny | 5 to 10 mph NE | 7% |
| Wednesday Night | 50°F | Mostly Cloudy | 0 to 5 mph NNE | 5% |
| Thursday | 68°F | Partly Sunny | 0 to 5 mph NNE | 4% |
| Thursday Night | 51°F | Partly Cloudy | 0 to 5 mph NNE | 4% |
| Friday | 70°F | Mostly Sunny | 0 to 5 mph NNE | 5% |
Forecast source: National Weather Service (api.weather.gov) for Union (42.232, -88.545). Updated through the day.
Growing snapshot for Union
Last spring frost
Apr 28
First fall frost
Oct 12
Growing season
166 days
Hardiness zone
5b
More local growing data for Union: nearby ZIP 60180 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
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Climate data from the nearest NOAA station, Marengo, Il (5.3 mi from Union). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.