Last updated: June 2, 2025
Understanding the UV Index is essential for residents of Mercer Island, United States, as it plays a crucial role in safeguarding our skin health and preventing sunburn. With a climate characterized as Csb, Mercer Island experiences varying UV levels throughout the day, peaking at 9 around midday. By being aware of the UV Index, you can better protect yourself and your loved ones from harmful effects of sun exposure, ensuring enjoyable outdoor activities while minimizing risks. Keep an eye on those UV levels and stay sun-safe!
The UV Index data reveals a dynamic daily pattern of sun exposure. Starting gently at 1 at 7:00 AM, it gradually climbs, reaching 3 by 9:00 AM. The intensity peaks at 9 around 1:00 PM, signaling the highest risk for UV-related harm. As the afternoon progresses, the index dips, falling back to 5 by 4:00 PM, and dropping to 1 again by 7:00 PM. With such fluctuations, it’s essential to protect your skin during the peak hours of 11:00 AM to 2:00 PM when the UV Index hits 7 and above. Always remember, even on mild days, sunscreen and protective clothing are your best allies!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 3 | moderate | 30 min |
| 10:00 | 5 | moderate | 30 min |
| 11:00 | 7 | high | 25 min |
| 12:00 | 8 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so do UV levels, significantly impacting sun exposure and skin safety for visitors and residents. January to March sees a gradual increase in UV Index, peaking with a moderate level in March at 5, where the burn time decreases to 30 minutes. The high-risk months, characterized by extremely high levels of UV radiation, are May through August, with indices soaring to 9 and enforcing a burn time of just 15 minutes. Following this, September presents a moderate risk with an index of 7, and a burn time of 25 minutes, before dropping again in October with a moderate index of 5. November and December then return to lower risks, emphasizing a UV Index of 2 and 1, respectively, allowing for longer safe exposure times of 45 minutes. To minimize the risk of UV-related harm, visitors and residents should take extra precautions during the high-risk months by wearing sunscreen, protective clothing, and limiting sun exposure during peak hours.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mercer Island | 2 | 3 | 5 | 6 | 8 | 9 | 9 | 8 | 7 | 5 | 2 | 1 |
| Chicago UVI | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |
| Brooklyn UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| New York City UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |