When a high pressure system forms over the Great Basin—usually during the fall—it pushes air masses downwards, causing compression that results in winds in California that elevate temperatures upwards of 100°F (38°C). These winds can reach speeds well over 75 miles (120 kilometers) per hour in many cases, blowing down into the densely populated coastal regions. The dry winds of the Santa Ana help create conditions that make brush fires in the hills around Los Angeles and other cities much more likely. In fact, one of the most disastrous fires in California’s history—known as the Cedar Fire—occurred in October 2003 as a result of strong Santa Ana winds. The fire destroyed 721,791 acres (2,921 square kilometers) of land and burned 3,640 homes to the ground.