Last updated: July 2, 2025
Understanding the UV Index is crucial for residents and visitors in Longwood, Saint Helena, Ascension and Tristan da Cunha, as it plays a significant role in protecting skin health and preventing sunburn. With peak UV levels reaching 8 during the midday hours, awareness of these risks can help you enjoy the beautiful climate while safeguarding your skin from harmful effects. The BWh climate of Longwood brings plenty of sunshine, making it essential to check UV forecasts regularly to ensure safe outdoor activity, particularly during those hours when the sun's rays are most intense. Stay informed and enjoy the outdoors responsibly!
At dawn, the UV Index remains low, peaking at 1 by 08:00. As the sun rises higher, a notable increase occurs, reaching 3 at 09:00 and escalating dramatically to a maximum of 8 from 12:00 to 13:00. This midday surge indicates a higher risk for sun exposure, making it essential to take precautions such as wearing sunscreen and protective clothing. The intensity then gradually declines, dropping to 4 by 15:00, and continuing its descent to 0 by 19:00, marking the end of the sun’s peak influence for the day. Stay mindful of these hourly fluctuations to enjoy the sun safely!
| 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 | 8 | very high | 15 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 6 | 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 |
| Longwood | 15 | 15 | 13 | 12 | 9 | 8 | 8 | 10 | 11 | 14 | 14 | 15 |
| Jamestown 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 |