Last updated: May 3, 2025
Understanding the UV Index is crucial for Los Altos, where the mild Csb climate often gives way to intense sun exposure. Knowing the daily UV levels not only helps in preventing painful sunburns but also plays a significant role in maintaining long-term skin health. With peak UV Index values reaching 10 around midday, residents and visitors should be particularly vigilant during these hours to minimize risks associated with UV radiation. By staying informed about UV Index fluctuations throughout the day, you can enjoy the beautiful California sunshine while protecting your skin.
The UV Index data unveils a dynamic progression of sun intensity throughout the day. Starting low at 1 at 07:00, the index gradually escalates, reaching maximum levels of 10 between 12:00 and 14:00. This peak signals a critical time for sun protection. As the afternoon wanes, the index tapers off to 8 at 15:00, and then descends further to 3 by 17:00, and 2 by 18:00. Ultimately, the day concludes softly with a return to 1 at 19:00. It's essential to stay vigilant during those peak hours to safeguard your skin while enjoying the sun!
| 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 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 10 | very high | 15 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 |
The UV Index experiences significant seasonal variation, with the highest risks typically occurring from March to August. During this period, the UV Index peaks at 11, indicating an extreme exposure category in June and July, where the burn time is as short as 10 minutes. Conversely, the months of January, November, and December present a lower risk with a moderate UV Index of 3 to 5, allowing for burn times up to 30 minutes. It is crucial for both visitors and residents to monitor the UV Index regularly, especially during the high-risk months, and to take appropriate sun protection measures, such as wearing sunscreen, protective clothing, and seeking shade during peak hours to prevent skin damage.
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 Altos | 3 | 5 | 8 | 9 | 10 | 11 | 11 | 10 | 9 | 7 | 5 | 3 |
| 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 |