Last updated: June 2, 2025
In Karlstejn, Czech Republic, being aware of the UV Index is crucial for protecting your skin and overall health. The UV Index measures the strength of sun’s ultraviolet (UV) rays, helping residents and visitors alike understand when it’s essential to apply sunscreen or seek shade to prevent sunburn and long-term skin damage. With a Cfb climate, Karlstejn experiences varying UV levels throughout the day, especially peaking between 11:00 AM and 3:00 PM when values can soar to as high as 8. Understanding these levels is vital for enjoying the sunshine safely in this beautiful historic town.
The UV Index throughout the day presents a clear and vigorous pattern of intensity. As the sun rises at 07:00, the index starts at a gentle 1, indicating minimal risk. By 08:00, it climbs to 2, still in the low range, but things escalate quickly; by 09:00, it reaches 3. The sun's power peaks astonishingly at 12:00, hitting a maximum of 8, which signifies a high risk for unprotected skin. This intense exposure persists until 14:00, before gradually tapering off through the afternoon. By 15:00, the index drops to 7, then diminishes further to 5 at 16:00, and continues to decline into the evening hours, settling back down to 1 by 19:00. Those planning outdoor activities during the midday hours should take care to protect themselves from the sun’s powerful rays!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | 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 | 8 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index exhibits significant seasonal changes, reflecting varying risks associated with sun exposure. The months of May through August are particularly high-risk, with UV Index values reaching 7 (high) and 8 (very high), resulting in shorter burn times of 15 to 25 minutes. Visitors and residents should take extra precautions during this period, such as wearing sunscreen, protective clothing, and sunglasses, especially between 10 AM and 4 PM. As the year transitions to September and October, UV levels decrease moderately but still warrant caution until they drop to low levels in November and December, where burn times increase back to 45 minutes. Staying informed and adopting preventative measures is essential to avoid skin damage and enjoy the outdoors safely year-round.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Karlstejn | 2 | 3 | 4 | 5 | 7 | 8 | 8 | 7 | 6 | 4 | 2 | 1 |
| Prague UVI | 2 | 3 | 4 | 5 | 7 | 8 | 8 | 7 | 6 | 4 | 2 | 1 |
| Ostrava UVI | 2 | 2 | 4 | 6 | 7 | 8 | 8 | 7 | 6 | 4 | 2 | 1 |
| Olomouc UVI | 2 | 3 | 4 | 6 | 7 | 8 | 8 | 7 | 6 | 4 | 2 | 2 |
| Pilsen UVI | 2 | 3 | 5 | 6 | 8 | 8 | 8 | 7 | 6 | 4 | 2 | 1 |
| Brno UVI | 2 | 3 | 5 | 6 | 8 | 8 | 8 | 7 | 6 | 4 | 2 | 2 |