As of 2:51 AM PDT on July 12, 2025, all 33 cities in San Mateo County, CA in our database have a UV Index reading of 0, indicating no radiation from the sun.
Over the next 24 hours, the highest UV Index reading in San Mateo County, CA is expected to be 11.1 in Portola Valley between 1:00 PM - 2:00 PM PDT today.
Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
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Color | |||||
Risk | Low | Moderate | High | Very High | Extreme |