Santa Ana Winds

News: Santa Ana winds-driven wildfires have burned over 4,000 acres and impacted approximately 22,000 people in the coastal town of Malibu, California.

About Santa Ana Winds

• Definition– Santa Ana winds are dry and warm (often hot) winds in the Southern California area that blow in from the desert — which includes the Great Basin of the western United States, incorporating Nevada and part of Utah.
• Seasonal Occurrence– Santa Ana conditions can occur whenever the Great Basin is cooler than Southern California, usually between September and May. However, they are most notable in October, as Southern California’s climate during autumn increases the risk of wildfires.
• Formation and effect:
  • Santa Ana winds occur when high pressure forms over the Great Basin, located between the Rocky Mountains and the Sierra Nevada, while low pressure develops along California’s coast.
  • This pressure difference drives strong winds from the inland deserts of the Basin, east and north of Southern California, over the mountains toward the Pacific Ocean.
  • As the winds move down the mountains, they compress and heat up, causing their humidity to drop, often below 20% and sometimes even below 10%.
  • The resulting dry conditions turn vegetation into highly flammable material, which contributed to fueling the flames in Malibu.