Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Sumas, Washington, where the combination of a temperate Cfb climate and varying sunlight exposure can elevate UV risks throughout the day. With maximum UV levels reaching as high as 9 between noon and 1 PM, it's essential to monitor these readings to prevent sunburn and long-term skin damage. By being aware of the UV Index, you can make informed decisions about sun safety, ensuring your outdoor activities remain enjoyable while protecting your skin’s health against harmful UV rays.
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 |
Throughout the year, the UV Index reflects significant seasonal changes that impact sun exposure and potential skin damage. The high-risk months are from April to August, where the UV Index peaks at 9 in July, indicating very high exposure risk with a burn time as low as 15 minutes. Visitors and residents are advised to take extra precautions during these months, including wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade during peak sun hours. Meanwhile, the winter months of January and February see a drop in UV levels to 2 and 3, classified as low to moderate, allowing for more lenient sun exposure while still taking care to protect skin. As the UV Index generally decreases towards the end of the year, exposure caution can be relaxed, particularly in November and December when burn times extend back to 45 minutes.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sumas | 2 | 3 | 5 | 6 | 7 | 8 | 9 | 8 | 6 | 4 | 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 |