Environmental Factors

Climate at Cabrillo National Monument

Cabrillo National Monument enjoys a Mediterranean climate characterized by warm, dry summers and cool, mild winters. Weather data is recorded at Lindbergh Field in San Diego, directly across the bay from the monument. The average annual temperature is 64°F, with rainfall averaging 9.5 inches annually, though it can vary significantly from 3.4 inches to 19.4 inches. Most of the rainfall occurs during the winter months, from November to April.

Cyclic Weather Patterns

The weather at Cabrillo National Monument is influenced by cyclical patterns driven by the Southern Oscillation (El Niño/La Niña) and the Pacific Decadal Oscillation. These ocean-atmospheric conditions alter the position of the winter jet stream, causing it to shift either northward or southward. When the jet stream moves southward, it typically results in warm, wet winters in San Diego.

Temperature and Seasonal Variations

San Diego is known for its warm, sunny weather, with coastal temperatures regulated by the Pacific Ocean throughout the year. In the fall, strong high pressure over the desert, combined with an incoming low-pressure system over the Pacific Ocean, can cause a sudden shift in wind direction from westerly to easterly. This results in a rapid drop in relative humidity, a spike in temperatures, and the formation of strong easterly winds known as Santa Ana winds. These winds, a type of Foehn wind, are common in the fall and early winter months across southern California and northern Baja California.

Fog and Moisture

Nature compensates for the lack of rain when cold air from the ocean meets the warm air on the land, resulting in dense fogs. This fog adds moisture to the environment, allowing species requiring more water to coexist with desert plants and animals.

Unique Ecosystem

The unique climate conditions at Cabrillo National Monument support a diverse ecosystem. Mild coastal temperatures allow heat-loving cacti to grow alongside evergreen shrubs common in cooler climates. Salamanders can be seen walking past sunning desert snakes, and mosses thrive in cool shade near parched lichens clinging to dry, hot boulders. This biodiversity is a testament to the adaptability of nature in response to the region's varying climatic conditions.

 

The Role of Fire at Cabrillo National Monument

Fire plays a critical role in shaping the southern California landscape. When conditions are right, it can cause vast ecological and financial damage. However, recent research has shown that fire has been a part of this landscape for millennia.

Historical Fire Activity

Despite its coastal location, which buffers the Point Loma peninsula from extreme drought and wind events that drive mega-fires in southern California, research indicates that wildfires did occur here in the past. Evidence of this is found in the park's flora, which includes several fire-dependent species. For example, Ceanothus verrucosus requires fire for the successful germination of its seeds. The widespread presence of this species across the peninsula suggests that wildfires historically burned in Point Loma, facilitating the propagation of C. verrucosus. Examination of the seed bank at Cabrillo National Monument has revealed several "fire-following" species lying dormant, awaiting fire to germinate.

Fire Frequency

While fire is relatively more frequent in the San Diego foothills and mountains, occurring at intervals of 15-50 years, coastal fires are thought to have much longer intervals, ranging from 100-250 years. Many coastal fire-dependent species are long-lived or have seeds that remain viable for centuries.

Current Fire Management Challenges

The lack of connectivity to other natural areas, surrounding urban development, and the presence of sensitive adjacent military structures have all but eliminated fire from the Point Loma ecosystem. Park managers and researchers are concerned that the absence of fire will result in the extirpation of several fire-dependent species, some of which are considered rare and of special interest.

In conclusion, while fire is a natural and historical part of the Point Loma landscape, current conditions and management practices present significant challenges in maintaining the ecological balance and biodiversity of Cabrillo National Monument.