Like the rest of the Bay Area, the San Francisco Peninsula has a coastal Mediterranean climate. In climates of this type, the main part of the growing season occurs from October to June, but there are diverse groups of organisms active all year round. Adaptations to summer drought by both plants and animals are an ongoing focus of research at Jasper Ridge Biological Preserve, as are the effects of microclimates.
Local precipitation increases sharply with altitude.
Multi-year droughts are common, and both the timing and amount of precipitation within a given growing season are extremely erratic. Summer fog drip plays an important role in maintaining soil moisture. Since 1983, automated weather stations have recorded temperature, precipitation, shortwave radiation, photosynthetically active radiation, relative humidity, and wind velocity hourly and daily from one to several sites in the Preserve. Plots of selected data from recent years at the preserve are available for viewing. JRBP weather data files are available on our secure data server for affiliates of the Preserve.