UV Index in Ontario, United States

Last updated: August 1, 2025

Understanding the UV Index in Ontario, United States, is crucial for anyone who enjoys the outdoors. With the potential for sunburn and long-term skin damage, being aware of daily UV levels can help protect your skin and overall health. Ontario's Dfb climate often leads to varying UV exposures, especially during the peak sun hours from late morning to early afternoon when the index can reach as high as 10. By staying informed about the UV Index, residents can take proactive measures against harmful rays and enjoy their time outside safely.

Hourly UV Index in Ontario

As the sun climbs higher in the sky, the UV Index rises dramatically throughout the morning and into the afternoon. Starting at a modest 1 at 7:00 AM, the levels gradually escalate, reaching 2 by 8:00 AM and hitting 4 by 9:00 AM. The intensity peaks at 10 around 1:00 PM, marking the most critical time for sun safety. From this peak, the index gently descends, dropping to 9 at 2:00 PM and then tapering down to 3 by 5:00 PM. As evening approaches, the UV Index diminishes to a gentle 1 by 7:00 PM. It's essential to stay protected during the mid-day heat, especially when the UV levels are at their highest.

Average solar exposure data for the current time of the year. Actual values may vary and depend on many factors, such as cloud cover, vegetation cover, surface type, etc.
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	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

Monthly UV Index Trends in Ontario

Throughout the year, seasonal UV changes significantly impact exposure levels, with the highest UV Index recorded during the summer months. High-risk months include April through September, where the UV Index reaches very high levels of 8 to 10, leading to a burn time as short as 15 minutes. In contrast, January and December present lower UV levels, categorized as low, allowing for burn times of up to 45 minutes. Visitors and residents are strongly advised to take precautions during high-risk months by applying sunscreen, wearing protective clothing, and seeking shade during peak sunlight hours to minimize the risk of skin damage.

Monthly Maximum UV Index for Ontario, United States

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Ontario. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.

Data source: Statistical UV Index data for Ontario, based on information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

Compare Ontario UV Index with Other United States Cities

The table above highlights how UV exposure in Ontario compares to other major locations across United States. This comparison helps travelers and residents better understand regional sun intensity and plan outdoor activities with sun safety in mind.

Ontario's solar exposure compared to other cities in United States. Generated using Copernicus Atmosphere Monitoring Service information.
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Ontario	2	4	5	8	9	10	10	9	8	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