Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Saint Jo, United States, where sunny days are frequent and UV exposure can be intense. Keeping track of UV levels not only helps in preventing sunburn but is also vital for maintaining long-term skin health. With a humid subtropical climate that features hot summers, the UV Index can soar to significant heights—reaching a peak of 11 at midday. By being aware of these fluctuations, you can take proactive measures to protect yourself and enjoy the outdoors safely.
At 07:00, the UV Index is a gentle 1, signaling a low level of UV radiation. As the sun climbs, it gradually rises, reaching a moderate 3 by 09:00. The intensity peaks spectacularly at 12:00 with a powerful 10, indicating a high risk of harm from unprotected sun exposure. For those brave enough to venture out, it's crucial to take precautions, especially between 13:00 and 14:00, when it hits its zenith at 11. The afternoon sees a slow decline, tapering down to 5 by 17:00 and further reducing to a mild 2 as evening approaches at 18:00. Finally, the day concludes with the UV Index dropping back to a safe 1 by 19:00, making for a relaxing end to a sun-soaked day.
| 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 | 10 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 10 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, ultraviolet (UV) exposure fluctuates significantly, necessitating awareness among residents and visitors. From January to April, the UV Index begins to rise, starting at a moderate level of 4 and peaking at 10 in April, indicating a shift to very high exposure. The months of May through August present the highest risk, with the UV Index consistently at an extreme 11, where the burn time reduces to just 10 minutes. Following this peak, September and October see a slight decrease, with the UV Index returning to 10 and 8, respectively, both still classified as very high. By November and December, levels drop back down to high and moderate categories with indices of 6 and 4, allowing for safer outdoor activities but still requiring caution. Residents and visitors should take protective measures, especially during the high-risk months of May to August, by wearing sunscreen, protective clothing, and seeking shade during peak sunlight hours to minimize the risk of UV 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 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Saint Jo | 4 | 6 | 8 | 10 | 11 | 11 | 11 | 11 | 10 | 8 | 6 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |