Acorn Dropping reaches a crescendo early this month in the Cuyamaca, Laguna, and Palomar mountains. Wiry scrub oaks, massive canyon live oaks, and the golden-leaved black oaks all contribute to the growing collection of acorns littering the ground. Acorn woodpeckers are busy stuffing acorns into the small holes they drill into the bark of pine trees. Beneath the trees, the browns of bracken fern and the reds of poison oak and squaw bush are among the last expressions of autumn color we'll see in the mountains this year.
Local Temperatures should be declining most rapidly during this time of year, according to more than a century of local meteorological records. With every successive week, daily maximum temperatures are declining by about 3/4° Fahrenheit, and daily minimum temperatures are plummeting by about 1° Fahrenheit. (This gradual onset of fall/winter chill is probably all but unnoticed by most newcomers from harsher climates.) By January, our mean temperature will have fallen to about 55°, from an average temperature of about 70° in August.
Monarch Butterflies arrive along the California coast this month, migrating from their summer homes in the Sierra Nevada and the Rocky Mountains. Some 25 of the 260 wintering sites on the West Coast lie within San Diego County. The local sites include Presidio Park in San Diego, the UCSD campus, Quail Botanical Gardens in Encinitas, and Hosp Grove in Carlsbad.