McHenry County, IL: Current UV Index and Hourly Forecast

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As of 5:47 PM CDT on June 29, 2026, all 40 cities in McHenry County, IL in our database have a UV Index reading of Moderate. The city with the highest UV Index reading right now is Riley, IL with a reading of 3.1.

Over the next 24 hours, the highest UV Index reading in McHenry County, IL is expected to be 10 in Crystal Lake between 1:00 PM - 2:00 PM CDT tomorrow.

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Current UV Index in Cities in McHenry County, IL

• Alden - 3
• Algonquin - 3
• Big Foot Prairie - 3
• Bull Valley - 3
• Burtons Bridge - 3
• Cary - 3
• Chemung - 3
• Coral - 3
• Crystal Lake - 3
• Fox River Grove - 3
• Franklinville - 3
• Greenwood - 3
• Harmony - 3
• Hartland - 3
• Harvard - 3
• Hebron - 3
• Holiday Hills - 3
• Huntley - 3
• Island Lake - 3
• Johnsburg - 3
• Lake in the Hills - 3
• Lakemoor - 3
• Lakewood - 3
• Lawrence - 3
• Marengo - 3
• McCullom Lake - 3
• McHenry - 3
• Oakwood Hills - 3
• Pistakee Highlands - 3
• Prairie Grove - 3
• Richmond - 3
• Ridgefield - 3
• Riley - 3.1
• Ringwood - 3
• Solon Mills - 3
• Spring Grove - 3
• Trout Valley - 3
• Union - 3
• Wonder Lake - 3
• Woodstock - 3