Last updated: June 2, 2025
In Diamond Bar, California, staying informed about the UV Index is crucial for protecting your skin and overall health. Understanding UV levels helps residents effectively manage sun exposure, minimizing the risk of sunburn and long-term skin damage. With a mild Mediterranean climate, Diamond Bar typically experiences elevated UV exposure, especially from late spring to early fall. During peak hours, particularly between 11 AM and 1 PM, UV Index values can soar to dangerous levels, making it vital for locals to stay vigilant and take necessary precautions to safeguard their skin while enjoying the beautiful Southern California sunshine.
The UV Index reaches its peak intensity at 1 PM, soaring to an alarming 12. Early morning starts off gently, with indices of 1 at 7 AM and gradually rising to 2 by 8 AM. By 9 AM, the index jumps to 4, hinting at more intense sun exposure to come. As the day progresses, it escalates rapidly, hitting 7 by 10 AM and 9 at 11 AM. The sun is at its zenith at noon, with a robust 11. After this peak, a slight decline begins, but caution is still advised as the values remain significant, dropping to 8 at 3 PM and tapering off to 3 by 5 PM. The UV risk diminishes further into the evening, returning to a calmer 1 by 7 PM. Stay protected during those midday hours to enjoy the sun safely!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
During the year, UV Index values show significant seasonal variation, peaking in the summer months. High-risk months for UV exposure include March through August, particularly notable in June and July, where the UV Index reaches an extreme level of 12 and 11, respectively, with a burn time of only 10 minutes. Visitors and residents are advised to take necessary precautions during these months, such as wearing protective clothing, using broad-spectrum sunscreen, and limiting sun exposure, especially between 10 AM and 4 PM. As UV levels decrease from September onward, with moderate levels returning in the winter months of November and December, maintaining sun safety remains important, especially during high-exposure periods.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 |
| Diamond Bar | 4 | 6 | 8 | 10 | 10 | 12 | 11 | 10 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |