Mountain and Valley Winds
Downslope Winds occur when warm/dry air descends rapidly down a mountain side. These are common on the east side of the Rocky Mountains, called Chinook Winds. These winds can blow over 40 mph, and can occur in sudden gusts that are even stronger, which can make driving hazardous. In addition, their dry conditions increase the risk of wildfires in the area.
Santa Ana Winds occur when air from a region of high pressure over the dry, desert region of the southwestern U.S. flows eastward towards low pressure located off the California coast. This creates dry winds that flow east to west through the mountain passages in Southern California. These winds are most common during the cooler months of the year, occurring from September through May. Santa Ana winds typically feel warm (or even hot) because as the cool desert air moves down the side of the mountain, it is compressed, which causes the temperature of the air to rise. These strong winds can cause major property damage. They also increase wildfire risk because of the dryness of the winds and the speed at which they can spread a flame across the landscape.