Union, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Union, a village in Mchenry County, Illinois.
Today
83°F
Mostly Sunny
Mostly sunny, with a high near 83. South southwest wind around 10 mph, with gusts as high as 20 mph.
7-day forecast for Union
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 83°F | Mostly Sunny | 10 mph SSW | 1% |
| Tonight | 66°F | Chance Showers And Thunderstorms | 5 to 10 mph WSW | 63% |
| Wednesday | 77°F | Showers And Thunderstorms Likely | 5 mph WSW | 74% |
| Wednesday Night | 61°F | Showers And Thunderstorms | 0 to 5 mph NNW | 77% |
| Thursday | 78°F | Chance Rain Showers then Slight Chance Showers And Thunderstorms | 0 to 5 mph NE | 49% |
| Thursday Night | 59°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 0 mph | 15% |
| Friday | 81°F | Mostly Sunny | 0 to 5 mph SE | 5% |
| Friday Night | 62°F | Mostly Clear | 0 to 5 mph SSW | 8% |
| Saturday | 83°F | Mostly Sunny | 0 to 10 mph SSW | 11% |
| Saturday Night | 68°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 5 mph SSW | 20% |
| Sunday | 84°F | Slight Chance Showers And Thunderstorms | 5 to 10 mph SW | 20% |
| Sunday Night | 68°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 43% |
| Monday | 83°F | Chance Rain Showers | 5 mph SSW | 43% |
| Monday Night | 67°F | Chance Showers And Thunderstorms | 5 mph WNW | 45% |
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 Aug 4, 2026.