Low-Lying Temperature Inversions commonly occur in San Diego as winter approaches. During the night and morning hours, a meteorological condition often occurs in which the “normal” higher-you-go-the colder-it-gets trend is reversed. At such times cold marine air lies below a stable layer of warmer air originating from inland locales. Whenever moist air is trapped below a low-lying inversion layer, dense fog forms on or near the ground, and San Diego International Airport is sometimes forced to suspend operations.
The Fremont Cottonwoods along the San Diego River in Mission Gorge are now showing off their best autumnal foliage. You can park at the Old Mission Dam historic site or the Mission Trails Regional Park visitor center and explore the riparian area by way of riverside trails or by walking, bike riding, or skating along the bike path high above the river’s south and east banks. Large cottonwoods can also be seen along other watercourses throughout the San Diego County backcountry, including along the Sweetwater River near Cottonwood Golf Course, and in Cottonwood Valley, east of Pine Valley along Interstate 8.