Last updated: June 2, 2025
In San Ysidro, awareness of the UV Index is crucial for safeguarding your skin and overall health under the sun. With peak UV levels reaching up to 13 during midday hours, understanding these fluctuations can significantly aid in sunburn prevention and long-term skin health. Located in a BWk climate zone, San Ysidro experiences bright, sunny days that pose notable exposure risks, making it essential to stay informed about UV conditions. Protect yourself and your loved ones by knowing when to seek shade, apply sunscreen, and cover up to enjoy the sun safely!
Throughout the day, the UV Index experiences a dynamic shift, peaking at an impressive 13 between 1 PM and 2 PM, indicating a high risk of harm from unprotected sun exposure. The morning starts gently, with a UV Index of 1 at 7 AM, gradually rising to 4 by 9 AM. As the sun inches higher, the intensity increases sharply, reaching 10 by 11 AM and soaring to 12 by noon. Post-peak, the index begins to decline, dropping to 10 at 3 PM, before settling back to a mild 2 by 6 PM. This clear progression emphasizes the importance of sun protection during the midday hours when the UV Index is at its highest. Enjoy the sunshine, but remember to stay safe! ☀️
| 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 | 10 | very high | 15 min |
| 12:00 | 12 | extreme | 10 min |
| 13:00 | 13 | extreme | 10 min |
| 14:00 | 12 | extreme | 10 min |
| 15:00 | 10 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV radiation levels fluctuate significantly, with the highest risk occurring between March and September. During this period, the UV Index reaches extreme levels, peaking at 13 in June, where the recommended burn time is just 10 minutes. April, May, July, August, and September also maintain extreme ratings, advising caution and proactive sun protection strategies. February and October present high to very high UV conditions, with slightly longer burn times of 25 and 15 minutes, respectively. January and December see a reduction to moderate UV levels, allowing for a more relaxed approach to sun exposure. Visitors and residents should stay vigilant, applying sunscreen, wearing protective clothing, and seeking shade during peak sun hours, particularly from March through September.
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 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |
| San Ysidro | 5 | 7 | 10 | 12 | 12 | 13 | 12 | 12 | 11 | 8 | 6 | 5 |