UV index in San Francisco De Borja
Hourly ultraviolet index forecast for San Francisco De Borja, computed for clear sky.
Clear sky value. Thick cloud lowers the real index, but ultraviolet goes through thin cloud and reflects off sand, snow and water.
Daily maximum
15.4
Extreme (11 and above)
Oct 16, 2026 · America/Lima
What to do
Extreme (11 and above)
Avoid midday sun. Sunburn in minutes.
Daily maximum
| Day | Index | Category |
|---|---|---|
| Oct 16, 2026 | 15.4 | Extreme (11 and above) |
| Oct 17, 2026 | 14.6 | Extreme (11 and above) |
| Oct 18, 2026 | 15.4 | Extreme (11 and above) |
Hour (UTC time)
| Hour | Index | Category |
|---|---|---|
| 10/16/26, 1:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 2:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 3:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 4:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 5:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 6:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 7:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 8:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 9:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 10:00 AM UTC | 0.0 | Low (0 to 2) |
| 10/16/26, 11:00 AM UTC | 0.1 | Low (0 to 2) |
| 10/16/26, 12:00 PM UTC | 1.1 | Low (0 to 2) |
| 10/16/26, 1:00 PM UTC | 3.8 | Moderate (3 to 5) |
| 10/16/26, 2:00 PM UTC | 7.8 | Very high (8 to 10) |
| 10/16/26, 3:00 PM UTC | 12.0 | Extreme (11 and above) |
| 10/16/26, 4:00 PM UTC | 14.8 | Extreme (11 and above) |
| 10/16/26, 5:00 PM UTC | 15.4 | Extreme (11 and above) |
| 10/16/26, 6:00 PM UTC | 13.5 | Extreme (11 and above) |
| 10/16/26, 7:00 PM UTC | 9.7 | Very high (8 to 10) |
| 10/16/26, 8:00 PM UTC | 5.5 | High (6 to 7) |
| 10/16/26, 9:00 PM UTC | 2.1 | Low (0 to 2) |
| 10/16/26, 10:00 PM UTC | 0.4 | Low (0 to 2) |
| 10/16/26, 11:00 PM UTC | 0.0 | Low (0 to 2) |
| 10/17/26, 12:00 AM UTC | 0.0 | Low (0 to 2) |
Index
| Range | What to do |
|---|---|
| Low (0 to 2) | You can stay outside with no special protection. |
| Moderate (3 to 5) | Shade around midday, hat, sunglasses and sunscreen. |
| High (6 to 7) | Avoid the sun between 10 am and 4 pm; SPF 30 or higher. |
| Very high (8 to 10) | Unprotected skin burns fast; cover up and stay in the shade. |
| Extreme (11 and above) | Avoid midday sun. Sunburn in minutes. |
Choose a city
- Miraflores187,401 inhabitants
- San Isidro68,309 inhabitants
- Santa Anita - Los Ficus184,614 inhabitants
- Santiago de Surco251,648 inhabitants
- Jesus Maria66,171 inhabitants
- Lima7,737,002 inhabitants
- Breña81,909 inhabitants
How to read this page
How to read the UV index
The scale starts at 0 and has no ceiling: 3 to 5 calls for protection, 8 to 10 is very high, above 11 extreme. The 15.4 peak for San Francisco De Borja applies at the Sun’s highest moment, not all day.
Where the data comes from
The series comes from MET Norway (clear-sky UV index parameter), computed for the coordinates of San Francisco De Borja, refreshed at 2026-10-16T01:18:06Z. Licensed CC BY 4.0.
Clear sky, not real sky
The index assumes clear sky: under thick cover the real value in San Francisco De Borja is lower. This page is informational and does not replace medical advice on skin and sun exposure.
Protection in practice
At index 3 or above, the World Health Organization advises shade in the middle of the day, a shirt, a broad-brimmed hat, UV-filtering sunglasses and sunscreen reapplied through the day.
Understanding the UV index in San Francisco De Borja
What is the UV index in San Francisco De Borja today?
The forecast UV peak in San Francisco De Borja is 15.4 (Extreme (11 and above)), around 10/16/26, 5:00 PM UTC. 22 hours of the day sit at 3 or above, and 17 at 6 or above.
A very high or extreme peak: in San Francisco De Borja unprotected fair skin starts to burn within minutes in the middle of the day, and shade stops being optional. Over the coming days the highest forecast value is 15.4, on Oct 16, 2026.
How long can I stay in the sun in San Francisco De Borja?
Avoid midday sun. Sunburn in minutes. The index depends on how high the Sun is, on the thickness of the ozone layer, on altitude and on what stands in the way: San Francisco De Borja lies at 12.09° of latitude, and the peak always falls near solar noon, not clock noon. Sand, snow and water reflect radiation and add to what comes from above.
The value on this page is computed for clear sky: under thick cloud the real figure in San Francisco De Borja sits below 15.4, but thin cloud barely filters UV — which is exactly why sunburn on an overcast day is so common.
Words on this page
UV index
An open-ended scale starting at 0 that measures the strength of ultraviolet radiation able to redden skin. From 3 to 5 protection is already advised, 8 to 10 is very high and above 11 is extreme. It depends on how high the Sun is, on the ozone layer, on altitude and on cloud.
Standard definition by WHO / WMO — Global Solar UV Index · UV index
Ultraviolet radiation
The invisible part of sunlight with wavelengths below violet. UVB burns skin and is largely filtered by the ozone layer; UVA goes deeper, passes through glass and ages skin. The UV index sums both up by their reddening effect.
Standard definition by WHO / WMO — Global Solar UV Index · Ultraviolet radiation
Ground-level ozone
Ozone formed near the ground when sunlight reacts with exhaust gases and solvents. It is not the ozone layer, which sits kilometres up and protects us: this one irritates the airways and rises on clear, hot, windless days.
Standard definition by U.S. EPA — AQI Technical Assistance Document · Ground-level ozone
AQI
The United States Air Quality Index, 0 to 500, which converts each pollutant concentration into a single score and reports the worst one. Up to 50 is good, above 100 it starts to affect sensitive groups, above 150 it affects everyone. The score is not linear in concentration: it follows breakpoints set by the EPA.
Standard definition by U.S. EPA — AQI Technical Assistance Document · AQI
Preliminary data
A measurement published as soon as it is collected, before the agency’s final review. It can be corrected or withdrawn: earthquake magnitudes shift in the first hours, air-quality readings are revised weeks later. Use it to plan your day, not for regulatory or legal purposes.
Data from 10/16/26, 1:18 AM UTC
- MET Norway — Locationforecast 2.0 (ultraviolet_index_clear_sky)Licence: CC BY 4.0 e NLOD 2.0 (uso comercial permitido) · Credit: Dados do MET Norway (Instituto Meteorológico da Noruega)O índice é calculado para céu limpo: com nuvens espessas o valor real pode ser menor.
- GeoNames cities15000Licence: CC BY 4.0 · Credit: Dados de cidades: GeoNames (CC BY 4.0)
- Dados de cidades: GeoNames (CC BY 4.0)
How to read these numbers
The curve rises to solar noon, which rarely matches noon on the clock, then falls. Use the daily maximum row to plan when to go out.
Frequently asked questions
- What is the UV index in San Francisco De Borja today?
- The highlighted value is the maximum forecast for San Francisco De Borja today; the table carries the hourly curve in UTC.
- Why are the times in UTC?
- The source publishes in UTC and we would rather not convert without showing the arithmetic. The city time zone appears next to its name.
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