My favorite time of year runs from the summer solstice until around Halloween. San Francisco's climate experiences its greatest dynamic range during these four months. Days can be sunny and clear with temperatures in the small garden micro-climate easily passing 100°F. At the other extreme, thick coastal fog can keep out the sun for weeks at a time, and soak the garden like a rain. Cool ocean air will leave you shivering in the middle of summer. The tomatoes won't grow but the fuchsias and tree ferns respond with lush growth during the long days.
All your hopes and expectations as a gardener are bound up in these variations. I want the hot weather to ripen my summer vegetables. I want the cold fog to blunt the effects of California's long summer drought. Ideally, I want to walk the line between the two extremes. This time of year, we garden on the edge.
Foggy days bring out the romance and mystery of this place. Sunny summer days inspire less introspection. The sunny day climaxes around 4 p.m. when the light gives up everything it has left to give.