Marine air moderates parts of Zone 14 that otherwise would be colder in winter and hotter in summer. The opening in Northern California’s Coast Ranges created by San Francisco and San Pablo bays allows marine air to spill much farther inland. The same thing happens, but the penetration is not as deep, in the Salinas Valley. Zone 14 includes the cold-winter valley floors, canyons, and land troughs in the Coast Ranges from Santa Barbara County to Humboldt County.
The milder-winter, marine-influenced areas in Zone 14 and the cold-winter inland valley within Zone 14 differ in humidity. For example, lowland parts of Contra Coasta County are more humid than Sacramento.
Fruits that need winter chill do well here, as do shrubs needing summer heat (oleander, gardenia). Over a 20-year period, this area had lows ranging from 26 to 16º F (–3 to –9ºC). Weather records show all-time lows from 20 down to 11ºF (–7 to –12º C).