Last updated: May 3, 2025
In St. Thomas, Canada, staying informed about the UV Index is crucial for safeguarding your skin against harmful sun exposure. With UV levels peaking between hours 11:00 AM and 3:00 PM—reaching a maximum of 9—understanding these fluctuations can help you effectively prevent sunburn and protect your overall skin health. St. Thomas experiences a Dfb climate, characterized by warm summers and cold winters, which means that even during the cooler months, UV exposure can be significant. By monitoring the UV Index, you can enjoy outdoor activities while minimizing the risks associated with intense sunlight. Stay safe and informed!
As the sun rises, the UV Index begins its ascent, starting at a mild 1 at 07:00. By 08:00, it climbs to a 2, indicating a low risk of harm from unprotected sun exposure. However, from 09:00 onwards, the intensity builds, peaking at 9 between 13:00 and 14:00—a time when precautions are essential to protect skin from damage. The afternoon hours see a slight decrease, dropping to 8 at 15:00 and further declining to 4 by 17:00. As the sun sets, the UV Index falls back down to 1 by 19:00, marking a return to safer levels. Stay vigilant during those midday hours to enjoy the sunshine while keeping your skin healthy!
| 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 | 9 | very high | 15 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so does the UV Index, which indicates the strength of ultraviolet radiation and the potential for skin damage. From January to March, the UV Index remains at a moderate level (3-5), allowing for longer exposure times of about 30 minutes without significant risk of sunburn. However, as April approaches, the UV Index spikes to 8, categorized as very high, and this trend continues through the summer months of May and June, reaching a peak of 10 in July. These months represent the highest risk for sunburn, where just 15 minutes of exposure can lead to skin damage. As summer wanes into August and September, the UV Index begins to decrease but remains in the very high category, emphasizing the need for caution. By October, the risk diminishes to a high level (6), and the burn time increases to 25 minutes, transitioning into the cooler months of November and December, when the UV Index falls to 4 and 2 respectively. Residents and visitors are advised to take precautions, especially during the high-risk months of April through September, by wearing sunscreen, protective clothing, and seeking shade during peak sunlight hours.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Edmonton UVI | 2 | 3 | 5 | 6 | 7 | 7 | 8 | 7 | 6 | 4 | 2 | 1 |
| Calgary UVI | 2 | 3 | 4 | 6 | 8 | 8 | 9 | 8 | 7 | 4 | 2 | 1 |
| Montreal UVI | 2 | 4 | 5 | 7 | 9 | 9 | 8 | 8 | 7 | 5 | 3 | 2 |
| Ottawa UVI | 2 | 4 | 5 | 8 | 9 | 9 | 8 | 8 | 7 | 5 | 3 | 2 |
| Toronto UVI | 2 | 4 | 5 | 8 | 9 | 9 | 9 | 9 | 7 | 5 | 3 | 2 |
| St. Thomas | 3 | 4 | 5 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |