Last updated: July 2, 2025
In St. Thomas, Canada, being aware of the UV Index is crucial for protecting your skin from harmful solar radiation. Understanding UV levels is essential not only for preventing sunburn but also for promoting overall skin health, especially during the sun's peak hours. With a climate classified as Dfb, locals and visitors alike face varying UV exposure risks throughout the day. As the index soars to a maximum of 10 around 1 PM, knowing how to shield yourself can make all the difference in enjoying the beautiful outdoors safely.
The UV Index data illustrates a dynamic shift throughout the day, peaking in the afternoon hours. Starting at a mild 1 at 7 AM and 8 AM, the index climbs steadily, reaching a distinctive 3 by 9 AM. By 11 AM, it surges to 7, and the intensity escalates further with a peak of 10 at 1 PM—making it the most critical time for sun exposure. As the afternoon progresses, the index gradually declines, settling at 6 by 4 PM and tapering off to 1 by 7 PM. This data serves as a crucial reminder to take sunscreen precautions especially between 11 AM and 2 PM, when the sun’s rays are the strongest.
| 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 | 10 | 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 |