Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors of Nantucket, where sun exposure can significantly impact skin health. High UV levels, particularly during peak hours—reaching a maximum of 10 at noon—underscore the importance of sunburn prevention strategies. As this charming island experiences a temperate Cfa climate, awareness of UV risks not only helps protect against immediate skin damage but also reduces the risk of long-term health issues. Stay informed to enjoy Nantucket’s sun-filled days while safeguarding your skin!
As the sun rises, the UV Index begins at a low 1 at 7:00 AM, gradually climbing as the day unfolds. By 8:00 AM, it reaches 3, signaling a mild increase in UV exposure. The intensity peaks between 12:00 PM and 1:00 PM, with the index hitting a maximum of 10, indicating a high risk of harm from unprotected sun exposure. Thankfully, the afternoon brings a decrease, with values declining to 7 at 3:00 PM and dropping further to 1 by 7:00 PM, as the sun sets. This data emphasizes the importance of sun protection during the midday hours when exposure is at its highest.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 10 | 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 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index experiences notable fluctuations, with the highest risk months occurring from March to September, when the index consistently ranges between 6 and 10. Specifically, April to August feature very high levels, with peak values reaching 10 in June and July, corresponding to a dangerously short burn time of 15 minutes. In contrast, January and December present lower UV risks, categorized as moderate to low, with corresponding burn times of 30 minutes and 45 minutes, respectively. To safeguard your skin, it is crucial for visitors and residents to adopt protective measures, especially during the peak months by using sunscreen, wearing protective clothing, and seeking shade during midday hours to reduce UV exposure effectively.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nantucket | 3 | 5 | 6 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 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 |