Last updated: June 2, 2025
In Princeton, United States, being aware of the UV Index is essential for protecting your skin and maintaining overall health. Understanding UV levels is crucial not just for avoiding painful sunburns but also for reducing the long-term risks of skin damage and other health issues. With a Dfb climate, Princeton experiences seasonal variations in UV exposure, which can peak significantly—reaching levels of 9 during midday hours. By staying informed about UV conditions, residents can enjoy the sun safely while safeguarding their skin against harmful radiation.
The UV Index rises steadily throughout the morning, peaking at 9 between 11:00 AM and 1:00 PM, making these hours the most intense for sun exposure. Early risers will encounter a more manageable index of 2 at 7:00 AM, quickly escalating to 3 by 8:00 AM. As the day progresses, outdoor enthusiasts should remain cautious, as the index hits 7 at 10:00 AM and reaches its maximum. After this midday peak, the UV rays begin to decline, falling to 8 at 2:00 PM and gradually tapering off to a more benign 1 by 6:00 PM. Stay protected and enjoy the sun safely!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 7 | 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, the UV Index demonstrates notable seasonal changes, with higher values typically occurring during the late spring and summer months. From April through August, UV levels peak, particularly in May and June, where the index reaches 9, indicating a very high risk of harm from unprotected sun exposure and a burn time of just 15 minutes. July and August maintain UV levels of 8, also classified as very high. High-risk months are particularly concentrated from April to September, where residents and visitors are advised to take protective measures, such as wearing sunscreen, protective clothing, and seeking shade during the peak sun hours. Conversely, winter months such as January and December present a much lower risk, with a UV Index of 2 and low exposure category, allowing for more time outdoors without significant risk. It's crucial for everyone to stay informed on local UV levels and adjust sun safety practices accordingly, particularly during the high exposure months.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Princeton | 2 | 4 | 5 | 7 | 9 | 9 | 8 | 8 | 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 |