Last updated: May 3, 2025
Understanding the UV Index is crucial for residents of Princeton, United States, as it serves as a vital indicator of the sun’s intensity and potential risks. With the region’s Dfb climate, Princeton experiences seasonal variations that can influence UV exposure levels, often peaking in the summer months. Knowledge of UV levels not only aids in sunburn prevention but also supports long-term skin health—helping you make informed decisions about outdoor activities. During peak hours, particularly between noon and 2 PM, the UV Index can reach levels as high as 9, signaling a significant risk for harm without appropriate protection. Stay informed and protect your skin while enjoying all that Princeton has to offer!
As the sun rises, the UV Index begins its ascent, starting at a mild 1 at 07:00. By 09:00, it ramps up to a moderate 4, signaling outdoor enthusiasts to take caution. The peak intensity hits at 12:00 and 13:00, where the UV Index reaches an impressive 9, making proper sun protection essential. From there, it gradually declines, dropping to a 5 by 16:00, and finally settling back down to 1 by 19:00. This hourly fluctuation highlights the importance of being sun-safe during the midday hours, when UV exposure is at its strongest. Stay protected and enjoy the sun wisely!
| 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 | 8 | very high | 15 min |
| 15:00 | 6 | high | 25 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 |
Throughout the year, UV levels fluctuate significantly, with high-risk months generally spanning from April to August. During this period, particularly in May and June, the UV Index peaks at 10, indicating a very high risk of harm from unprotected sun exposure, with a rapid burn time of just 15 minutes. Comparatively, the UV Index is moderate in the winter months of January to March, and again in October and November, where the burn time extends to 30 minutes. As the year progresses into December, the UV risk decreases further, classified as low, allowing for a safer 45-minute exposure before burning. Visitors and residents are advised to be vigilant in the spring and summer months, taking necessary precautions such as applying sunscreen, wearing protective clothing, and seeking shade during the peak sun hours to minimize the risks of skin damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Princeton | 3 | 4 | 5 | 8 | 9 | 10 | 10 | 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 |