Last updated: August 1, 2025
Understanding the UV Index in Princeton, United States is crucial for safeguarding your skin and promoting overall health. With the area's Dfa climate characterized by warm summers, knowing the UV levels can help you effectively prevent sunburn and long-term skin damage. The UV Index climbs to its peak at midday, reaching levels of 10 around noon, indicating a high risk of harm from unprotected sun exposure. By staying informed about these daily fluctuations, you can enjoy Princeton's sunny days while minimizing the risks associated with harmful UV radiation. Remember, a little awareness goes a long way in preserving your skin’s health!
At dawn, 7:00 AM, the UV Index is a mild 1, offering a gentle start to the day. As the sun climbs higher, it steadily rises, reaching 2 by 8:00 AM and hitting 3 at 9:00 AM. However, between 10:00 AM and 1:00 PM, the intensity increases sharply, peaking at an impressive 10 from 12:00 PM to 1:00 PM—the highest level of risk. The UV Index then begins its descent, dropping to 8 at 3:00 PM, followed by a gradual decline to 4 by 5:00 PM. As evening approaches, the index wanes further, settling back down to 1 by 7:00 PM. To enjoy the sunshine while staying safe, make sure to take precautions, especially during those peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 3 | moderate | 30 min |
| 10:00 | 5 | moderate | 30 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 | 8 | very high | 15 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, the UV Index exhibits notable seasonal changes, with high-risk months typically occurring from April to August. In these months, the UV Index reaches its peak at 11, indicating an extreme exposure category, particularly in June and July where burn time is reduced to just 10 minutes. Visitors and residents should take extra precautions during this period, including wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade, especially from midday to early afternoon when UV radiation is strongest. As summer transitions into fall, the UV Index gradually decreases, with moderate levels seen from November to March, allowing for safer outdoor activities during these months. Being aware of these variations can help individuals enjoy the outdoors while minimizing the risk of UV-related health effects.
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 |
| Princeton | 3 | 5 | 6 | 9 | 10 | 11 | 11 | 9 | 8 | 6 | 4 | 3 |
| 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 |