Last updated: May 3, 2025
Understanding the UV Index is crucial for residents and visitors in Jamestown, Saint Helena, Ascension and Tristan da Cunha. With its unique climate classified as BWh, the region experiences varying UV levels throughout the day, peaking at an alarming 9 between noon and 1 PM. Awareness of these UV levels is essential not only for sunburn prevention but also for maintaining long-term skin health. As the sun can be deceptively strong, even when the UV Index appears low in the early hours, it's important to stay informed to protect yourself during peak exposure times.
As the sun rises, the UV Index starts off low at a comfortable 1 from 7:00 AM to 8:00 AM. By 9:00 AM, it jumps to 3, signaling a gradual increase in sun exposure. The intensity peaks around 12:00 PM, reaching an impressive 9, making midday the most critical time for sun safety. As the afternoon unfolds, the index slowly declines; it drops to 7 by 2:00 PM, then further decreases to 4 at 3:00 PM. The later hours offer a gentle reprieve, with values falling to 1 by 5:00 PM and ultimately 0 by 6:00 PM. Remember, during those peak hours, it’s essential to protect your skin!
| 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 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 9 | 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 |
Throughout the year, UV Index levels display significant seasonal variations, with extreme levels persisting from January to April and again in September to November. The highest UV Index is recorded in the first four months of the year, peaking at 15, necessitating a cautious approach with a burn time of only 10 minutes. As temperatures rise, the UV Index decreases slightly in May and June, yet still maintains a very high category, allowing for a burn time of 15 minutes. The late summer months, particularly August, report slightly elevated levels before dropping again in the fall. Visitors and residents should take special care during high-risk months, particularly from January to April and September to November, by using appropriate sun protection strategies such as sunscreen, wearing protective clothing, and seeking shade during peak hours to minimize sun exposure and risk of skin damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Edinburgh of the Seven Seas UVI | 14 | 13 | 11 | 7 | 4 | 3 | 3 | 5 | 8 | 10 | 12 | 15 |
| Jamestown | 15 | 15 | 13 | 12 | 9 | 8 | 8 | 10 | 11 | 14 | 14 | 15 |
| Longwood UVI | 15 | 15 | 13 | 12 | 9 | 8 | 8 | 10 | 11 | 14 | 14 | 15 |
| Half Tree Hollow UVI | 15 | 15 | 13 | 12 | 9 | 8 | 8 | 10 | 11 | 14 | 14 | 15 |
| Georgetown UVI | 14 | 14 | 14 | 13 | 12 | 10 | 10 | 11 | 12 | 13 | 14 | 14 |