Last updated: July 2, 2025
Understanding the UV Index is essential for residents of Alliston, Canada, especially during the sunniest summer days. The UV Index serves as a crucial tool for preventing sunburn and protecting your skin health by indicating the strength of ultraviolet radiation from the sun. With Alliston's Dfb climate, which features warm summers, the risk of harmful UV exposure rises significantly, particularly around midday when the index peaks at 9. By staying informed about the UV levels, you can enjoy the outdoors while taking necessary precautions to safeguard your skin against damage.
The UV Index today shows a dynamic rise and fall throughout the hours, peaking in the midday sun. Starting from a gentle 1 at 07:00, it gradually climbs to reach 8 by 12:00, just before the sun reaches its zenith. The intensity spikes to its highest point of 9 at 13:00, remaining high until 14:00, when it begins to taper off. By 15:00, it drops to 7, continuing its downward trend to 4 by 17:00, and then easing back to the safer 1 by 19:00. Remember to protect yourself during the peak hours, especially between 11:00 and 14:00, when the sun’s rays are strongest!
| 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 | 7 | high | 25 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 |
Throughout the year, UV exposure varies significantly, with the highest risk months occurring from April to August, where the UV Index consistently reaches 9, classifying it as very high. During these months, the burn time is a mere 15 minutes, emphasizing the need for caution. As winter approaches, the UV Index decreases, dropping to 2 in January and December, indicating a low risk of UV exposure, while February and March see moderate levels with indices of 4 and 5, respectively. Visitors and residents should prioritize protective measures such as using sunscreen, wearing protective clothing, and seeking shade, especially in the spring and summer months, when the sun's intensity is at its peak. Staying informed and alert can help mitigate the risks associated with UV exposure year-round.
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 |
| Alliston | 2 | 4 | 5 | 8 | 9 | 9 | 9 | 9 | 7 | 5 | 3 | 2 |
| Toronto UVI | 2 | 4 | 5 | 8 | 9 | 9 | 9 | 9 | 7 | 5 | 3 | 2 |