Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Petersburg, United States, where sunshine can be both a blessing and a risk. With the city experiencing a humid subtropical climate (Cfa), the potential for high UV exposure makes it essential to be aware of UV levels throughout the day. Knowing these levels not only helps in preventing sunburn but also plays a key role in maintaining long-term skin health. During peak hours, such as noon to mid-afternoon when the UV Index can soar to 11, minimizing sun exposure and wearing protective clothing becomes especially important. Stay informed and protect yourself against the harmful effects of UV radiation while enjoying Petersburg's beautiful weather!
At dawn, the UV Index starts gently, peaking at 1 by 07:00 and 08:00, making it a safe time for early morning strolls. As the day progresses, the intensity gradually increases, reaching 4 by 10:00 and soaring to a striking 9 by noon. The sun reaches its zenith around 13:00, with a blistering 10, and even escalates to an impressive 11 by 14:00—the highest point of the day. As afternoon turns to evening, the index retreats; it dips to 8 by 16:00 and further down to a moderate 3 by 18:00, offering a more comfortable environment for outdoor activities. By 19:00, the UV intensity settles at a humble 2, signalling that the sun is winding down, making way for a lovely evening.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 2 | low | 45 min |
| 10:00 | 4 | 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 | 11 | extreme | 10 min |
| 15:00 | 10 | very high | 15 min |
| 16:00 | 8 | very high | 15 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 2 | low | 45 min |
Throughout the year, seasonal UV changes show a marked increase in exposure, particularly from March to August, when the UV Index peaks. The high-risk months are April, May, June, July, and August, with UV Index values reaching as high as 11 in June, categorized as extreme. During these months, the recommended burn time is sharply reduced to 10-15 minutes, making protective measures essential. Visitors and residents are advised to prioritize sun safety by seeking shade, wearing protective clothing, and applying sunscreen regularly, particularly during midday hours when UV radiation is strongest. In contrast, the winter months of January, February, and December present lower UV levels, categorized as moderate, where the burn time extends up to 30 minutes. However, even in these months, it's wise to remain vigilant against UV exposure, particularly on sunny days.
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 |
| Petersburg | 3 | 5 | 7 | 10 | 10 | 11 | 10 | 9 | 9 | 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 |