UV Index in Great Falls, United States

Last updated: May 3, 2025

Understanding the UV Index is crucial for residents of Great Falls, Montana, where the climate falls within the BSk zone. With its sunny days and fluctuating weather patterns, the UV levels can vary significantly throughout the day, peaking at 9 between 1 PM and 2 PM. Being aware of these levels is vital for preventing sunburn and safeguarding your skin health. By familiarizing yourself with the UV Index, you can better protect yourself from excessive exposure, ensuring that your outdoor activities remain enjoyable and safe under the sun.

Hourly UV Index in Great Falls

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!

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	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

Monthly UV Index Trends in Great Falls

The UV Index exhibits significant seasonal changes, with the highest levels occurring from April to August. During this peak period, particularly in May and June, the UV Index reaches 10 and 9, categorized as very high, indicating a burn time of only 15 minutes. Visitors and residents should pay special attention to April through August as these months represent the highest risk for UV exposure. In contrast, January, December, and November show much lower UV levels, categorized as low or moderate, allowing for longer exposure times of 30 to 45 minutes without significant risk. It is advisable for individuals to seek shade, wear protective clothing, and apply sunscreen, particularly during the high-risk months from April to August, to minimize the chance of skin damage.

Monthly Maximum UV Index for Great Falls, United States

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Great Falls. 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 Great Falls, 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 Great Falls UV Index with Other United States Cities

The table above highlights how UV exposure in Great Falls 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.

Great Falls'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
Great Falls	2	4	5	7	9	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