"Santanas," "Santa Anas" or "Devil Winds," are a phenomenon which occurs in the coastal regions of Southern California during the late fall and winter months. These winds are generally characterized by conditions of drastically low humidifies and high velocities. Effects on atmospheric temperatures are dependent upon the state of variable forces which affect the winds during their formation. Usually there is a marked temperature rise, especially if the Santana conditions persist over a prolonged period.      The initial formation of the Santana winds occurs as a large, cold air mass from the polar regions of the Pacific moves south into the arid interior areas of Utah, Nevada and eastern California. From these barren wastes, the mass travels south and south-westward, influenced by atmospheric pressure differentials between the interior areas and the reaches of the Pacific Ocean. As the currents flow across the arid deserts and into the passes and canyons of the coastal mountains, they are dried and heated. Under conditions of moderate barometric gradients, the winds funnel through the passes; compressing to increase velocities to gale force. If pressure gradients are excessive, the winds will pour directly over the mountains to strike the Los Angeles Basin a few miles south of the foothills. In such instances, great clouds of dust are raised to tinge the skies. Temperatures are raised by compressional heating as the wind currents descend to progressively lower levels.      As these winds whip through the mountains and across the surface of the coastal lowlands, every wisp of vegetation and every stick of wood is drained of any vestige of moisture. Relative humidity readings fall ominously and have been recorded as low as three and four percent.      The arrival of these winds on the coastal plain is presaged by clearing skies, starry nights, and a drop in temperatures. As the Santana begins to blow, temperatures rise and the relative humidity plummets rapidly. It is not unusual for Santana conditions to last for a week. With each passing hour, the fire danger increases.