McHenry County, IL: Current UV Index and Hourly Forecast

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As of 3:02 PM CDT on May 20, 2026, out of 40 cities in McHenry County, IL in our database, 35 cities (88%) have a UV Index reading of High, while 5 cities (13%) have a UV Index reading of Moderate. The city with the highest UV Index reading right now is Chemung, IL with a reading of 6.4.

Over the next 24 hours, the highest UV Index reading in McHenry County, IL is expected to be 7.6 in Crystal Lake between 12:00 PM - 1:00 PM CDT tomorrow.

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Current UV Index in Cities in McHenry County, IL

• Alden - 5.4
• Algonquin - 6.3
• Big Foot Prairie - 5.4
• Bull Valley - 6.3
• Burtons Bridge - 6.3
• Cary - 6.3
• Chemung - 6.4
• Coral - 6
• Crystal Lake - 6.3
• Fox River Grove - 6.3
• Franklinville - 6
• Greenwood - 5.4
• Harmony - 6
• Hartland - 6
• Harvard - 5.4
• Hebron - 5.4
• Holiday Hills - 6.3
• Huntley - 6
• Island Lake - 6.3
• Johnsburg - 6.3
• Lake in the Hills - 6.3
• Lakemoor - 6.3
• Lakewood - 6
• Lawrence - 6.4
• Marengo - 6
• McCullom Lake - 6.3
• McHenry - 6.3
• Oakwood Hills - 6.3
• Pistakee Highlands - 6.3
• Prairie Grove - 6.3
• Richmond - 6.3
• Ridgefield - 6.3
• Riley - 6.4
• Ringwood - 6.3
• Solon Mills - 6.3
• Spring Grove - 6.3
• Trout Valley - 6.3
• Union - 6
• Wonder Lake - 6.3
• Woodstock - 6