San Mateo County, CA: Current UV Index and Hourly Forecast

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As of 10:54 AM PDT on April 19, 2026, all 33 cities in San Mateo County, CA in our database have a UV Index reading of Moderate. The city with the highest UV Index reading right now is Pacifica, CA with a reading of 3.3.

Over the next 24 hours, the highest UV Index reading in San Mateo County, CA is expected to be 7.9 in Portola Valley between 1:00 PM - 2:00 PM PDT today.

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Current UV Index in Cities in San Mateo County, CA

• Atherton - 3.1
• Baywood Park - 3.1
• Belmont - 3.1
• Brisbane - 3.2
• Broadmoor - 3.2
• Burlingame - 3.1
• Colma - 3.2
• Daly City - 3.2
• East Palo Alto - 3.1
• El Granada - 3.3
• Emerald Lake Hills - 3.1
• Foster City - 3.1
• Half Moon Bay - 3.3
• Highlands - 3.1
• Hillsborough - 3.1
• La Honda - 3.3
• Ladera - 3.1
• Loma Mar - 3.3
• Menlo Park - 3.1
• Millbrae - 3.3
• Montara - 3.3
• Moss Beach - 3.3
• North Fair Oaks - 3.1
• Pacifica - 3.3
• Pescadero - 3.3
• Portola Valley - 3.3
• Redwood City - 3.1
• San Bruno - 3.2
• San Carlos - 3.1
• San Mateo - 3.1
• South San Francisco - 3.2
• West Menlo Park - 3.1
• Woodside - 3.1