Overview

• San Francisco International Airport data show an average maximum of 67°F from June 1 to July 15, marking the coldest start to summer since 1965.
• Despite the record low start, National Weather Service data describe this summer as mostly average, with only two days of above-average highs to date.
• A strong marine layer, cooler Pacific waters and the absence of a persistent high-pressure ridge have kept coastal highs in the 50s and 60s.
• Cities inland such as San Jose recorded 38 of the first 45 summer days cooler than the same period last year, while Livermore’s temperatures remain below long-term averages despite occasional heat spikes.
• Forecasters predict mid-60s highs and mid-50s lows will prevail through late July, with offshore wind events seen as the likely catalyst for any late-season warming.