UV Index in Wisconsin (WI)
Wisconsin has an average annual UV index of 3.7, classified as Moderate . UV levels peak in June with an average of 8, reaching Very High levels. During peak months, unprotected fair skin can burn in as little as 13 minutes. SPF 50+ sunscreen, protective clothing, and shade are strongly recommended. UV ranges from 3.9 in Door County to 4.3 in Milwaukee.
Monthly UV Index by City in Wisconsin
The heatmap below shows the monthly average UV index for 5 cities in Wisconsin. Colors range from green (low UV, 0-2) through yellow (moderate, 3-5), orange (high, 6-7), red (very high, 8-10), to purple (extreme, 11+). Hover over any cell to see the exact value.
| City | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Avg | Peak |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Milwaukee | 1 | 2 | 3 | 5 | 7 | 8 | 8 | 7 | 5 | 3 | 1 | 1 | 4.3 | June |
| Madison | 1 | 2 | 3 | 5 | 7 | 8 | 8 | 7 | 5 | 3 | 1 | 1 | 4.3 | June |
| Green Bay | 1 | 1 | 3 | 5 | 7 | 8 | 8 | 7 | 5 | 3 | 1 | 1 | 4.2 | June |
| Eau Claire | 1 | 1 | 3 | 5 | 7 | 8 | 8 | 7 | 5 | 3 | 1 | 1 | 4.2 | June |
| Door County | 1 | 1 | 3 | 4 | 6 | 8 | 8 | 7 | 5 | 3 | 1 | 0 | 3.9 | June |
Sun Protection Recommendations for Wisconsin
Based on the peak UV index of 8 (Very High) during June, here are the recommended sun safety measures for Wisconsin residents and visitors:
Very High UV — Very high risk of harm. Take extra precautions — unprotected skin can burn quickly.
- Apply SPF 50+ sunscreen generously, reapply every 90 minutes
- Wear UPF-rated clothing, wide-brimmed hat, and wraparound sunglasses
- Seek shade whenever possible
- Avoid outdoor activities between 10 AM and 4 PM if possible
- Be aware that sand, water, and concrete reflect UV and increase exposure
Recommended sunscreen: SPF 50+
Estimated Sunburn Times in Wisconsin (June Peak)
Approximate time to first sunburn at peak UV (8) without sunscreen, by skin type:
| Skin Type | Description | Time to Burn |
|---|---|---|
| Type I | Very Fair | 8 min (high risk) |
| Type II | Fair | 13 min (high risk) |
| Type III | Medium | 25 min |
| Type IV | Olive | 38 min |
| Type V | Brown | 50 min |
| Type VI | Dark Brown/Black | 63 min |
Seasonal UV Patterns in Wisconsin
Wisconsin's UV index follows a seasonal pattern, with the lowest levels in December and January and the highest in June. Here are the state-average UV levels by month:
Summer months in Wisconsin consistently reach Very High or Extreme UV levels. Outdoor workers, athletes, and beachgoers should take extra precautions from May through September.
How Wisconsin Compares to Other States
Below is a comparison of Wisconsin with five states that have similar average UV index levels. Understanding how your state compares helps put your sun exposure risk in context.
| State | Avg UV | Level | Cities |
|---|---|---|---|
| Wisconsin (WI) | 3.7 | Moderate | 5 |
| Michigan (MI) | 3.8 | Moderate | 6 |
| North Dakota (ND) | 3.8 | Moderate | 5 |
| Oregon (OR) | 3.8 | Moderate | 6 |
| Minnesota (MN) | 3.6 | Moderate | 5 |
| New Hampshire (NH) | 3.6 | Moderate | 5 |
Skin Cancer Risk Factors
UV radiation is the primary environmental risk factor for skin cancer. While the UV index in Wisconsin is only one factor, understanding cumulative exposure is important. Key risk factors include:
- Cumulative UV exposure — total lifetime sun exposure, especially sunburns before age 18
- Skin type — fair skin (Types I-II) has significantly higher risk
- Geographic location — Wisconsin's lower UV reduces but does not eliminate risk
- Altitude — higher elevations increase UV exposure significantly
- Outdoor occupation/hobbies — agricultural workers, construction workers, golfers, runners, and beach visitors accumulate more exposure
- Tanning bed use — artificial UV exposure dramatically increases risk
The American Academy of Dermatology recommends annual skin checks for everyone, with more frequent screenings for those with multiple risk factors. Early detection dramatically improves outcomes for all types of skin cancer.
Check UV for Your City
Use our UV index lookup tool to find your specific city in Wisconsin, or browse all 50 states to compare UV levels across the country.