Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors of Sao Joao da Boa Vista, Brazil, where the climate is characterized by warm summers and moderate sunshine. As the sun rises higher in the sky, UV levels can fluctuate significantly, reaching a peak of 7 around noon—an indicator that sunburn and skin damage can occur within minutes without proper protection. By keeping an eye on the UV Index, you not only safeguard your skin health but also enjoy the beautiful outdoors safely. With typical exposure risks peaking between late morning and early afternoon, awareness of these levels can help you plan your activities wisely and prevent harmful effects from the sun’s rays.
At dawn, the UV Index starts off low, with a maximum of 1 at 07:00 and 08:00. As the sun rises higher, it reaches 3 by 09:00, before climbing to a peak of 7 at 12:00. This midday intensity signifies a need for sun protection, especially during the height of the day when UV exposure is most potent. The index begins to decline in the afternoon, dropping to 5 at 14:00 and settling back to 1 by 17:00. By 18:00 and into the evening, the UV Index sharply drops to 0, marking a safe time to enjoy outdoor activities without the risk of sunburn. Stay sun-safe!
| 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 | 6 | high | 25 min |
| 12:00 | 7 | high | 25 min |
| 13:00 | 6 | high | 25 min |
| 14:00 | 5 | moderate | 30 min |
| 15:00 | 3 | moderate | 30 min |
| 16:00 | 1 | low | 45 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 0 | low | 45 min |
| 19:00 | 0 | low | 45 min |
The UV Index shows significant seasonal variation, with the highest readings occurring from January to April, where the index reaches an extreme 16. These months pose a high risk for sunburn, with a critical 10-minute burn time. After April, the index slightly decreases, but remains very high in May (8) and July (8), and high in June (7). As summer transitions into fall, the UV Index fluctuates but remains concerning, especially in September (12) and October (14), both categorized as extreme, again allowing only a short 10-minute exposure without protection. The end of the year is marked by high indices once more, peaking in December at 16. Visitors and residents are strongly advised to take protective measures against UV exposure, particularly during these high-risk months to minimize the risk of sunburn and long-term skin damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rio de Janeiro UVI | 15 | 14 | 13 | 10 | 7 | 6 | 7 | 9 | 11 | 12 | 13 | 15 |
| Sao Paulo UVI | 16 | 15 | 12 | 11 | 8 | 6 | 7 | 9 | 11 | 13 | 14 | 15 |
| Sao Joao da Boa Vista | 16 | 16 | 13 | 11 | 8 | 7 | 8 | 10 | 12 | 14 | 15 | 16 |
| Belo Horizonte UVI | 17 | 16 | 14 | 12 | 9 | 7 | 8 | 10 | 12 | 13 | 14 | 16 |
| Salvador UVI | 14 | 14 | 14 | 13 | 10 | 9 | 9 | 12 | 12 | 15 | 15 | 14 |
| Fortaleza UVI | 14 | 14 | 15 | 15 | 13 | 11 | 11 | 12 | 13 | 13 | 13 | 13 |