Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Rancho Cucamonga, where sunny days are a hallmark of the climate. Awareness of UV levels not only helps in preventing sunburn, but also plays a vital role in promoting skin health and reducing long-term risks such as skin cancer. With maximum UV readings often peaking at 12 during midday, the typical Csa climate poses notable exposure risks, especially between 10 AM and 3 PM. Staying informed about the UV Index can empower you to enjoy the sun safely while protecting your skin from its potentially harmful effects.
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 |
| Rancho Cucamonga | 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 |