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

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As of 9:35 AM PDT on June 19, 2026, out of 33 cities in San Mateo County, CA in our database, 21 cities (64%) have a UV Index reading of Moderate, while 12 cities (36%) have a UV Index reading of Low. The city with the highest UV Index reading right now is San Mateo, CA with a reading of 2.8.

Over the next 24 hours, the highest UV Index reading in San Mateo County, CA is expected to be 9.8 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 - 2.8
• Baywood Park - 2.8
• Belmont - 2.8
• Brisbane - 2.2
• Broadmoor - 2.2
• Burlingame - 2.8
• Colma - 2.2
• Daly City - 2.2
• East Palo Alto - 2.8
• El Granada - 2
• Emerald Lake Hills - 2.8
• Foster City - 2.8
• Half Moon Bay - 2
• Highlands - 2.8
• Hillsborough - 2.8
• La Honda - 2.8
• Ladera - 2.8
• Loma Mar - 2.8
• Menlo Park - 2.8
• Millbrae - 2
• Montara - 2
• Moss Beach - 2
• North Fair Oaks - 2.8
• Pacifica - 2
• Pescadero - 2.8
• Portola Valley - 2.8
• Redwood City - 2.8
• San Bruno - 2.2
• San Carlos - 2.8
• San Mateo - 2.8
• South San Francisco - 2.2
• West Menlo Park - 2.8
• Woodside - 2.8