Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors in Philadelphia, where the climate boasts hot summers and moderate seasons. Being aware of UV levels is essential not just for preventing sunburns, but also for maintaining long-term skin health. During peak hours, particularly between 11 AM and 2 PM, the UV Index can soar to as high as 9, indicating a heightened risk of skin damage. With Philadelphia's typical summer sun exposure, staying informed about UV levels can empower you to take necessary precautions and enjoy the outdoors safely.
The UV Index throughout the day tells a compelling story of sun exposure. Starting at a gentle 1 at 7:00 AM, it gradually rises, reaching 2 by 8:00 AM. As the clock ticks towards mid-morning, the intensity ramps up, peaking at 9 between 12:00 PM and 2:00 PM—the perfect time for a shaded respite or sunscreen application. By 11:00 AM, the index hits 7, signaling more significant sun intensity. As the afternoon wanes, it starts to dip, falling to 3 by 5:00 PM, and eventually returning to 1 by 7:00 PM. This data emphasizes the importance of sun protection, particularly during those peak hours, to ensure a safe and enjoyable day outdoors!
| 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 | 7 | high | 25 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV exposure varies significantly, with the highest risk months occurring from April to August, where the UV Index consistently reaches 9, classifying it as very high. During these months, the burn time is a mere 15 minutes, emphasizing the need for caution. As winter approaches, the UV Index decreases, dropping to 2 in January and December, indicating a low risk of UV exposure, while February and March see moderate levels with indices of 4 and 5, respectively. Visitors and residents should prioritize protective measures such as using sunscreen, wearing protective clothing, and seeking shade, especially in the spring and summer months, when the sun's intensity is at its peak. Staying informed and alert can help mitigate the risks associated with UV exposure year-round.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Philadelphia | 2 | 4 | 5 | 8 | 9 | 9 | 9 | 9 | 7 | 5 | 3 | 2 |
| 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 |