Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Boise City, where the BSk climate brings hot summers and significant sun exposure. Being aware of the UV levels helps in preventing sunburn and promoting long-term skin health, which are essential in a region where midday readings can reach as high as 12. From the gentle morning rays at 8:00 AM to the peak intensity at noon, the UV Index fluctuates dramatically, necessitating vigilance to protect against harmful effects. With Boise's typical exposure risks, especially during the summer months, staying informed can make all the difference for your skin’s well-being.
The UV Index starts off low in the early morning hours, peaking at a gentle 1 at 7:00 AM and 8:00 AM. As the day progresses, the index begins to rise sharply, hitting 3 by 9:00 AM. However, the sun's intensity truly escalates between 10:00 AM and 2:00 PM, with a striking peak of 12 at both 1:00 PM and 2:00 PM—a reminder to stay protected during the midday sun. The index then begins to gradually decline, dropping to 9 by 4:00 PM and settling to 2 by 7:00 PM. As evening approaches, it’s clear that the sun’s strength has diminished, offering a more comfortable environment for outdoor activities.
| 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 | 12 | 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 |