Last updated: August 1, 2025
Understanding the UV Index is crucial for residents and visitors in Sao Joao da Boa Vista, Brazil, especially given the region's Cfa climate, which can bring both sunny days and heightened UV exposure risks. By staying informed about UV levels, you can effectively prevent sunburn and promote better skin health. During peak hours, particularly from 10 AM to 2 PM, the UV Index can soar to 8, indicating a very high risk of harm from unprotected sun exposure. Safeguarding your skin while enjoying the beautiful outdoors is essential—let's explore how to navigate the sun safely in this vibrant Brazilian city!
At sunrise, the UV Index begins at a gentle 1 at 07:00, rising gradually as the sun climbs higher. By 09:00, it reaches 3, indicating a moderate level of UV radiation. The heat of the day peaks at 12:00 with a high of 8, suggesting it’s time to seek shade or apply sunscreen. As the afternoon progresses, the index slightly drops to 7 at 13:00 and continues to decline, settling at 3 by 15:00. As the sun starts to set, the risk diminishing to 1 at 17:00 and finally dropping to 0 by 18:00, signaling a safer time for outdoor activities as the day winds down. Be mindful of the midday sun to protect your skin!
| 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 | 7 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 7 | high | 25 min |
| 15:00 | 4 | moderate | 30 min |
| 16:00 | 2 | 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 |