Union, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union, a village in Mchenry County, Illinois.
Tonight
58°F
Rain Showers
Rain showers. Cloudy. Low around 58, with temperatures rising to around 61 overnight. South southeast wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for Union
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 58°F | Rain Showers | 15 mph SSE | 88% |
| Wednesday | 62°F | Rain Showers Likely | 15 mph SSW | 57% |
| Wednesday Night | 47°F | Chance Rain Showers | 15 mph SW | 30% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph WSW | 48% |
| Thursday Night | 41°F | Chance Rain Showers | 5 to 10 mph NW | 49% |
| Friday | 51°F | Slight Chance Rain Showers then Mostly Cloudy | 10 mph N | 20% |
| Friday Night | 33°F | Partly Cloudy | 0 to 5 mph NNW | 3% |
| Saturday | 51°F | Mostly Sunny | 0 to 5 mph WNW | 3% |
| Saturday Night | 33°F | Partly Cloudy | 0 mph | 6% |
| Sunday | 57°F | Mostly Sunny then Slight Chance Rain | 5 to 10 mph W | 17% |
| Sunday Night | 34°F | Mostly Clear | 0 to 5 mph W | 6% |
| Monday | 60°F | Sunny | 0 to 10 mph WSW | 2% |
| Monday Night | 39°F | Mostly Clear | 5 mph W | 2% |
| Tuesday | 61°F | Sunny | 5 mph WNW | 1% |
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
Algonquin
Bull Valley
Cary
Chemung
Coral
Crystal Lake
Fox River Grove
Franklinville
Greenwood
Harmony
Hartland
Harvard
Hebron
Huntley
Johnsburg
Lake Barrington
Lake in the Hills
Lakemoor
Lakewood
Lawrence
Marengo
McCullom Lake
McHenry
Oakwood Hills
Prairie Grove
Richmond
Ridgefield
Riley
Ringwood
Solon Mills
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 Nov 4, 2026.