Last updated: June 2, 2025
Being aware of the UV Index is crucial for residents and visitors of Sierra Madre, California, where the climate typically features warm summers and mild winters. Understanding UV levels is essential not only for preventing sunburn but also for maintaining overall skin health, especially during peak exposure hours. With UV Index values soaring to 12 by noon, the risks of harmful skin effects rise significantly. Whether you’re enjoying the beautiful outdoors or simply taking a stroll, staying informed about the UV Index can help you protect yourself from the sun’s intense rays while enjoying all that Sierra Madre has to offer.
As the sun rises, the UV Index gradually climbs, starting at a gentle 1 at 07:00. By 09:00, it peaks at 5, signaling a shift toward more intense sunlight. The intensity reaches its zenith at 12:00, hitting 12—a level that calls for cautious outdoor activities. As the afternoon wanes, the index remains high, registering 12 again at 13:00, before dipping slightly to 11 by 14:00. The intensity gradually decreases as the day progresses; by 15:00, it drops to 8, and further to 6 by 16:00. As the sun sets, the UV Index returns to safer levels, landing at 3 by 17:00, and finishing the day at a minimal 1 by 19:00. Stay sun-savvy and protect yourself during those peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 10 | very high | 15 min |
| 12:00 | 12 | 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 |
Throughout the year, the UV Index experiences significant fluctuations, with the highest levels occurring from March to August. March and April both exhibit a very high UV Index of 9 and 10, respectively, leading to a burn time of only 15 minutes. The peak months, May and June, are classified as extreme with a UV Index of 11 and 12, necessitating caution as the burn time reduces to just 10 minutes. July and August continue this trend, remaining in the extreme category, before a gradual decline in September to 10 (very high) and further down to high with an Index of 7 in October. The year wraps up with moderate levels in November and December, where the burn time increases to 30 minutes. Given these variations, residents and visitors should take extra precautions from March through October, particularly during May and June, by wearing protective clothing, applying high-SPF sunscreen, and seeking shade to minimize their risk of sunburn and long-term 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 Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Sierra Madre | 4 | 6 | 9 | 10 | 11 | 12 | 12 | 11 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |