Last updated: July 2, 2025
In Onset, Massachusetts, staying informed about the UV Index is vital for safeguarding your skin and overall health. With maximum UV levels peaking at 9 during the day, understanding these fluctuations helps prevent sunburn and long-term skin damage. Onset’s Cfa climate brings warm summers with increased sun exposure, raising the risk of harmful UV radiation. Whether enjoying outdoor activities or just soaking up the sun, being aware of the UV Index can empower residents to take necessary precautions and protect themselves effectively.
As the sun rises, the UV Index starts off relatively low, peaking at 1 at 7:00 AM. By 8:00 AM, it gently climbs to 2, but it’s not until 9:00 AM that the intensity begins to gather real momentum, reaching 4. The index rises sharply as the day progresses, hitting 6 by 10:00 AM, and then escalating to a striking 8 at 11:00 AM. The maximum intensity occurs at 12:00 PM and 1:00 PM, where it levels off at a high 9. This peak is maintained through 2:00 PM, after which the UV Index begins its descent, dropping to 7 at 3:00 PM, 5 at 4:00 PM, and further declining to 3 by 5:00 PM. By the evening, it gently falls back to 1 at both 6:00 PM and 7:00 PM, signaling a significant reduction in sun exposure. Overall, it's a day where protection from UV radiation is essential during peak hours!
| 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 | 8 | very high | 15 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 9 | 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 |
As the seasons change, the UV Index exhibits significant fluctuations, indicating varying levels of sun exposure risk. From January to March, the UV Index starts off in the moderate range (3-6), suggesting a burn time of 30 minutes in January and February, but decreases to 25 minutes in March. The high-risk months emerge from April to September, where the Index rises dramatically to the very high range (8-10), with a critical burn time dropping as low as 15 minutes in April, May, June, July, August, and September. October sees a decline back to a high UV Index (6), allowing for 25 minutes of exposure before burning, while November and December move back into moderate and low categories (4 and 2, respectively) with more forgiving burn times of 30 minutes and 45 minutes. Visitors and residents are strongly advised to take precautions during the high-risk months by wearing sunscreen, protective clothing, and seeking shade, particularly when the UV Index is at its peak in the summer months.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Onset | 3 | 5 | 6 | 8 | 9 | 10 | 9 | 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 |