Summer temperatures regularly reach highs in the 80s °F ( ~ 28 – 30 °C ) with nighttime usually in the upper 40s to lower 60s °F ( ~ 9 – 18 °C ) depending on elevation , distance from the ocean and degree of marine inversion present . Summer weather is dominated by a persistent Marine layer that can vary in depth . When the inversion layer drops below 300 – 500 feet , the higher elevations are deprived of marine influence and will often be subject to intense heat waves with daytime temperatures in the 95-105F ( ~ 35 – 40 °C ) range and extreme low humidity with elevated overnight lows that offer little relief from the heat . Such conditions can lead to fires that can occur even before the official State of California fire season starts in the Fall . Examples of such fires include the 2016 Loma Fire , the 2009 Lockheed Fire and the Summit Fire in 2008
Loma Fire
Loma Fire
Santa Cruz Mountains