UV Index in Ontario, United States

Last updated: May 3, 2025

Understanding the UV Index is essential for residents of Ontario, United States, as it provides crucial information about the sun's intensity and the potential risks associated with exposure. With peak UV levels reaching up to 10 during midday hours, awareness of these fluctuations is vital for preventing sunburn and protecting long-term skin health. Ontario's Csa climate brings warm summers with significant sun exposure, heightening the risks of harmful UV rays. By staying informed about the UV Index, you can take proactive steps to enjoy the outdoors safely while keeping your skin safe from damage.

Hourly UV Index in Ontario

The UV Index shows a clear trajectory of increasing intensity as the day unfolds. Starting from a mild level of 1 at 7:00 AM, it gradually ascends to 2 by 9:00 AM. The real surge occurs between 10:00 AM and 2:00 PM, peaking at a dangerous 10 at 2:00 PM, indicating a critical need for protection against harmful rays. As the sun begins to descend, the UV Index tapers off, declining to 5 by 5:00 PM, and finally settling back at 1 by 7:00 PM. This data serves as a reminder to stay vigilant under the sun, particularly during those peak hours when UV exposure can be at its 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	1	low	45 min
09:00	2	low	45 min
10:00	4	moderate	30 min
11:00	6	high	25 min
12:00	8	very high	15 min
13:00	9	very high	15 min
14:00	10	very high	15 min
15:00	9	very high	15 min
16:00	7	high	25 min
17:00	5	moderate	30 min
18:00	3	moderate	30 min
19:00	1	low	45 min

Monthly UV Index Trends in Ontario

Throughout the year, UV Index levels show notable seasonal changes, indicating varying levels of risk for sun exposure. The highest UV risk months are from May to September, with peak levels reaching 11 in June, categorizing this period as extreme, where the burn time is as short as 10 minutes. In contrast, the winter months of January, February, October, and November see moderate levels with an index ranging from 2 to 4, allowing for longer exposure times of 30 minutes before burns occur. As such, visitors and residents are advised to take extra precautions during high-risk months, especially in the summer, by wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade when necessary 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
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
Ontario	3	4	6	7	10	11	10	10	8	5	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