Last updated: June 2, 2025
In Portsmouth, United States, being aware of the UV Index is essential for protecting your skin and overall health. Understanding UV levels can help you prevent sunburn and lower the risk of long-term skin damage, especially when the sun is at its peak intensity. With Portsmouth's Cfa climate, residents and visitors often face varying UV exposure risks throughout the day, particularly during midday hours when values can soar to 10. Being informed about these levels empowers you to enjoy the sunshine responsibly while safeguarding your skin.
The UV Index is a dynamic measure of solar intensity throughout the day, peaking dramatically at 12:00 PM with a notable 9, reaching its zenith at 1:00 PM and 2:00 PM with a maximum value of 10. During this period, it's essential to protect your skin from harmful UV rays. Early morning hours remain quite low, peaking at just 1 by 08:00 AM, while by 10:00 AM the index climbs to 5. As the sun continues to rise, it climbs swiftly to 7 by 11:00 AM, making midday the crucial time for sunscreen and shade. As the afternoon wanes, the UV Index gradually decreases, falling back to 5 by 5:00 PM, and finally settling at 1 by 7:00 PM, signaling a safe return to outdoor activities. Stay vigilant and enjoy the sunshine safely!
| 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 | 10 | very high | 15 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index exhibits significant seasonal fluctuations, with the highest levels occurring during the summer months. From March to September, the UV index reaches high to very high levels, peaking in May, June, and July at an index of 10, indicating a burn time of just 15 minutes. April also sees very high exposure with an index of 9. The months of March and October feature higher indexes of 7 and 6 respectively, classified as high, while the winter months of January, February, November, and December are categorized as moderate with indexes ranging from 3 to 5, allowing for longer exposure times of 30 minutes. Therefore, residents and visitors are advised to exercise extra caution during the high-risk months of April to September by using sunscreen, wearing protective clothing, and seeking shade, particularly during peak sun hours, to minimize the risk of skin damage.
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 |
| Portsmouth | 3 | 5 | 7 | 9 | 10 | 10 | 10 | 9 | 8 | 6 | 5 | 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 |