UV Index in San Francisco, Peru

Last updated: July 2, 2025

Understanding the UV Index in San Francisco, Peru is essential for protecting your skin and overall health from harmful ultraviolet rays. With the UV levels peaking around noon, reaching as high as 12, being aware of these levels can significantly help in preventing sunburn and ensuring long-term skin health. San Francisco experiences a Cfb climate, characterized by mild temperatures and fog, but that doesn't diminish the risk of UV exposure during sunny periods. By monitoring the UV Index, residents and visitors can enjoy outdoor activities while keeping their skin safe from damage.

Hourly UV Index in San Francisco

The UV Index throughout the day reveals a dynamic range of solar intensity, peaking at 12 around noon. Starting the day gently, the index registers a low 1 at 7:00 AM, gradually rising to 2 by 8:00 AM. As the sun climbs higher, it reaches 5 by 9:00 AM, then surges to a robust 11 by 11:00 AM, signaling higher caution for outdoor activities. The peak at midday is a daunting 12, urging everyone to seek shade and wear protective gear. The intensity begins to taper off in the afternoon, dropping back to 8 at 2:00 PM and further to 5 by 3:00 PM. By the late afternoon, the index drops significantly to 1 at 5:00 PM and settles at 0 by 6:00 PM, giving a gentle reminder that the sun's might can vary dramatically throughout the day.

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	5	moderate	30 min
10:00	8	very high	15 min
11:00	11	extreme	10 min
12:00	12	extreme	10 min
13:00	11	extreme	10 min
14:00	8	very high	15 min
15:00	5	moderate	30 min
16:00	2	low	45 min
17:00	1	low	45 min
18:00	0	low	45 min
19:00	0	low	45 min

Monthly UV Index Trends in San Francisco

Throughout the year, the UV Index in this region remains consistently high, peaking at 17 during the winter months of January, February, and March, as well as again in November and October, all categorized as extreme exposure with a burn time of only 10 minutes. Other months like April (UV Index 16) and December (UV Index 16) also present significant risk. Although there is a slight decrease in the index during the summer months, it remains high, ranging from 11 to 13. Visitors and residents should take precautionary measures year-round, including wearing sunscreen, protective clothing, and sunglasses, especially during high-risk months when the UV Index exceeds 12 from April through November. Prioritizing skin protection is essential to prevent sunburn and potential long-term damage.

Monthly Maximum UV Index for San Francisco, Peru

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in San Francisco. 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 San Francisco, 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 San Francisco UV Index with Other Peru Cities

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

San Francisco's solar exposure compared to other cities in Peru. Generated using Copernicus Atmosphere Monitoring Service information.
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Callao UVI	14	14	14	12	10	9	10	11	12	13	14	13
Lima UVI	14	14	14	12	10	9	10	11	12	13	14	13
Trujillo UVI	15	15	15	14	12	11	11	11	13	14	14	14
Chiclayo UVI	14	15	15	14	13	11	11	12	15	14	14	13
Arequipa UVI	18	17	17	15	12	10	11	13	15	17	18	17
San Francisco	17	17	17	16	13	11	12	13	15	17	17	16