What happened to “Second Summer” in San Francisco? Here’s what comes next
September has passed the halfway mark in San Francisco, and what many know as “the second summer” has disappeared from the city.
The average daytime high temperature during the first 17 days of September was 68.3 degrees in San Francisco, just below the 30-year September normal of 70 degrees. The warmest day reached only 72 degrees, and came on the second of the month. Santa Rosa, Napa, Oakland and Concord recorded similar trends, with maximum temperatures averaging 1 to 3 degrees below normal.