This permanent water flow, rare in the Santa Monica Mountains, is critical for the maintenance of a number of rare species. Smaller tributaries of Cold Creek flow out of the core area of Stunt Ranch Reserve, providing a well-developed corridor of riparian habitat. This average value, however, obscures the extreme variability of rainfall between drought and flood years. In addition, rain in this region may fall with remarkable intensity for brief periods. In general, however, temperature conditions are moderated by the close proximity of the Pacific Ocean.
Frosts occur occasionally in winter.
The core reserve area of Stunt Ranch encompasses a mosaic of chaparral, live-oak woodland, riparian, and grassland communities. Riparian communities are particularly well developed, both on small tributary streams and along Cold Creek. The Ethel Stunt oak tree has also served as creative inspiration to the poets, artists, and photographers who have visited Stunt Ranch. Some of her branches and part of her canopy burned in the '93 Malibu fire, but the Ethel Stunt oak, like most of the oaks on the Stunt Ranch Reserve, was not seriously damaged by the wildfire. Both native and secondary grasslands are present on Stunt Ranch.