Last updated: July 2, 2025
Understanding the UV Index in Ontario, United States, is crucial for protecting your skin and overall health. With the potential for sunburn and long-term skin damage increasing with UV exposure, being aware of daily UV levels can empower you to take necessary precautions. Ontario's Dfb climate contributes to variable UV risks, particularly during summer when the sun's intensity peaks. As UV Index values can climb as high as 9 around midday, it's essential to stay informed and safeguard against harmful rays—because a little awareness can go a long way in preserving your skin health!
The UV Index for the day showcases a notable rise in intensity as the sun climbs higher in the sky. Starting at a low of 1 at 7:00 AM, the index gradually increases to a moderate level of 3 by 9:00 AM. However, from 10:00 AM onward, things heat up significantly, peaking at a scorching 9 from noon to 2:00 PM. As the afternoon progresses, the UV Index gradually dips back to a friendly 3 by 5:00 PM, then descends further to 1 by the time evening sets in. This pattern underscores the importance of sun protection during peak hours, especially between 11:00 AM and 2:00 PM, when UV levels are at their highest.
| 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 | 9 | 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 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the UV Index fluctuates throughout the year, residents and visitors should be mindful of the changing sun exposure levels. During the winter months of January and December, the UV Index remains low at 2, allowing for longer safe exposure times of up to 45 minutes. However, as spring approaches, notable increases occur: March sees a rise to 6 (high exposure), while April and May escalate to 8 and 10 respectively, classified as very high, with burn times dropping to just 15 minutes. The peak UV risks are in May and June when the index reaches its highest at 10, making those months particularly hazardous for skin health. July and August maintain high levels, with UV indexes of 9, so protective measures are crucial. As summer gives way to autumn, the UV Index declines to 7 in September (high) and 5 in October (moderate), increasing the burn time. Finally, November drops back to a moderate level of 3. It is advisable for everyone to utilize appropriate sun protection during the high-risk months of April through September, particularly during peak hours, to mitigate the risk of skin damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ontario | 2 | 4 | 6 | 8 | 10 | 10 | 9 | 9 | 7 | 5 | 3 | 2 |
| Chicago UVI | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |
| Brooklyn UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| New York City UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |