Summary - The basic pattern consists of high pressure off the coast of northern and central California, and troughing off southern California and the southcentral coast (Point Conception to central Baja). The westerlies start to become more active, and troughs and fronts move thru northwestern California and the Pacific Northwest. The overall pattern is a bit changeable as it usually is during transitional seasons, but longwave troughs will tend to be in the west-central Pacific (160-170W) and Great Basin-Rockies. Sea surface temperature influence continues to favor weak troughing along 30N from southwest of southern California and west of central Baja. This may continue to draw tropical airmasses north at times in the first part of October. Other tropical cyclones develop off southern Baja, but the usual pattern in October is for upper high pressure to build briefly to the north with hot weather in northcentral and central California, and the possibility of rain for Baja, western Mexico and Arizona/New Mexico, as tropical cyclone remnants turn inland and move quickly northeast into the southern Rockies and southwest Great Plains. After dry and windy conditions occur along the northern California coastal area on September 28th thru 30th, rain or showers develop the first few days of October, focusing on the 2nd-4th. Other troughs move thru with cool conditions recurring on October 4th-5th, and 8th.