Watch out for poison oak, which in fall has reddish leaves. Leaves are in three — “leaves in three, let it be.”

Leaves Are Beginning to Turn in coastal San Diego County’s riparian woodland and oak woodland habitats. The summer-green crowns of willows and sycamores are already fading to yellow and brown. Beneath the oaks, the deciduous poison oak is flushing red. Good places for autumn walks this month and next include San Clemente Canyon (Marian Bear) Park adjacent to Freeway 52, Los Peñasquitos Canyon Preserve north of Mira Mesa, and Wilderness Gardens Preserve east of Pala in North County.

As the Beach Season Winds Down, San Diego County’s coastline is padded by what is likely the deepest and widest accumulations of sand we’ll see this year. Many stretches of the coastline are vulnerable to powerful waves associated with winter storms. This wave action can pull sand off the beaches and deposit it offshore, leaving behind (especially in North County) nothing but cobble beds. During the spring and summer gentle wave action usually returns much of the sand, usually in time for the arrival of the summer tourists.

The Ghost of Summer Suns. Halloween is approaching, and this means that Arcturus, the star sparkling low in the west-northwest in twilight, is taking on its role as "the Ghost of Summer Suns." For several evenings centered on October 25th every year, Arcturus occupies a special place above your local landscape. It closely marks the spot where the Sun stood at the same time, by the clock, during hot June and July — in broad daylight, of course!

So, as Halloween approaches every year, you can see Arcturus as the chilly ghost of the departed summer Sun.

The above comes from the Outdoors listings in the Reader compiled by Jerry Schad, author of Afoot & Afield in San Diego County. Schad died in 2011. Planet information from SkyandTelescope.org.