Last updated: July 2, 2025
In Boise City, awareness of the UV Index is crucial for maintaining skin health and preventing sunburn. With its semi-arid BSk climate, residents face varying UV exposure risks, especially during the sunniest hours. Understanding UV levels empowers you to take proactive measures against harmful rays, particularly when the index peaks at 12 between 1 PM and 2 PM. Whether you're enjoying outdoor activities or simply soaking up the sun, staying informed can significantly impact your well-being and help you make safer choices under the bright Boise skies.
As the day unfolds, the UV Index begins its climb, starting at a mild 1 in the early morning hours (07:00 and 08:00). By 09:00, it nudges upward to 2, but it's not until 10:00 that it takes a notable leap to 4. The real intensity hits by midday, peaking at a striking 12 at 14:00, with the highest value recorded at 13:00 at 11. As we transition into the late afternoon, the index starts to decline: 11 at 15:00, followed by 9 at 16:00. The evening brings a welcomed drop, reflected in 3 at 18:00 and 2 at 19:00. Remember, during the peak hours (11:00 to 14:00), it’s crucial to protect your skin with sunscreen and seek shade to beat the heat!
| 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 | 10 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 12 | extreme | 10 min |
| 15:00 | 11 | extreme | 10 min |
| 16:00 | 9 | very high | 15 min |
| 17:00 | 6 | high | 25 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 2 | low | 45 min |
Throughout the year, the UV Index exhibits significant seasonal variations, peaking during the summer months of May to August, where it reaches extremes of 11 to 12. The highest risk occurs in May, June, and July, with burn times as short as 10 minutes under these conditions. March and April also present considerable UV exposure, categorized as very high, with burn times of just 15 minutes. Visitors and residents should exercise caution from late winter through summer, especially during these high-risk months, by seeking shade, wearing protective clothing, and applying broad-spectrum sunscreen regularly to minimize the risk of skin damage. As the season transitions into fall and winter, UV levels decrease, offering more moderate exposure from October to December.
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 |
| Boise City | 4 | 6 | 8 | 10 | 11 | 12 | 12 | 11 | 10 | 7 | 5 | 3 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |