September is the warmest month with an average high of and an average low of . Temperatures exceed on an average of 4.0 days annually. Fog and low overcast are common during the night and morning hours in the summer months, which are generally very dry except for occasional light drizzle from the fog. On rare occasions moisture moving up from tropical storms has produced thunderstorms or showers in the summer. Gusty westerly winds are also common in the afternoon during the summer. The highest summer temperature was on June 14, 1961, breaking a record of set in June 1960. A high of was recorded on July 17, 1988, and a high of was recorded on September 1, 2017. Until August 1, 1993, it had never reached in August, which is one of the foggier months in the area. Due to thermal inversions, summer temperatures in the higher hills are often much higher than at the airport.