Last updated: August 1, 2025
Staying informed about the UV Index in Philadelphia is essential for protecting your skin and overall health. With peak values soaring to 11 during the midday hours, understanding these UV levels can be a critical factor in preventing sunburn and long-term skin damage. Philadelphia's humid subtropical climate means that, especially during the warmer months, residents face significant UV exposure risks. Whether you're enjoying a day at the park or simply commuting, being aware of the UV Index can help you take proactive measures—like wearing sunscreen or protective clothing—so you can enjoy the vibrant Philadelphia summer safely!
Expect a sunny day with a fluctuating UV Index that peaks at 11 around midday. The morning starts off gentle, with values rising from 1 at 7:00 AM to 4 by 9:00 AM. As the sun climbs higher, the UV Index escalates sharply, reaching 9 by 11:00 AM and hitting its highest point of 11 at both 12:00 PM and 1:00 PM. After the sun’s zenith, the UV levels gradually decline, dropping to 10 at 2:00 PM and tapering off to 1 by 7:00 PM. Remember to protect your skin during those peak hours for 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 | 3 | 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 | 11 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so does the UV Index, which significantly impacts exposure levels throughout the year. January starts with a moderate UV Index of 4, allowing for a burn time of 30 minutes. However, February ramps up to a high index of 7, with a reduced burn time of 25 minutes. The peak months, from March through August, experience extreme UV levels, particularly in May and June, where the UV Index reaches 11 and burn times shrink to just 10 minutes. September and October see a slight decrease, yet still maintain a very high index of 9 and 8, respectively. The year concludes with lower levels in November and December. Visitors and residents should take special care during the high-risk months from March to August, ensuring proper sun protection measures, such as wearing sunscreen, hats, and protective clothing, to mitigate the risk of UV-related harm.
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 |
| Philadelphia | 4 | 7 | 8 | 10 | 11 | 11 | 11 | 11 | 9 | 8 | 6 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |