Cumulonimbus clouds, elderberry, orioles, and the full moon.
Cumulonimbus clouds, or thunderheads, are most likely to form over San Diego County's deserts and mountains during the latter part of the summer season, beginning about late July. The clouds appear by midafternoon —- often the result of moist, tropical air entering the county from the south or southeast. If intense, these cloud buildups are accompanied by enough rain to flood the desert washes and mountain drainages. When the weather pattern allows the movement of moist air beyond the mountain barriers, even coastal San Diego County can experience the cool spatter of raindrops and spectacular evening lightning displays.
Elderberry, a common bush or small tree found from San Diego County's coastal canyons to the mountain slopes around Julian and Palomar, is in fruit this month. The branches carry myriads of tiny bluish fruits covered with a white powder. The fruits have traditionally been used for various drinks and preserves.
Orioles, the bright yellow or yellow-orange-and-black birds seen flitting among the palm trees, are summer residents of San Diego County's coastal areas. A century ago, the orioles preferred to nest in sycamore trees, which were then more common in our area's river bottoms. Today these birds are most likely to take up residence in the planted or volunteer palm trees, where they obtain fiber to build their nests from the easily shredded fronds.
The full moon rises impressively from the east horizon at around 8 p.m. on July 17, very close to the time of sunset. Some folk names for the July full moon include "hay moon," "wort moon," "moon of blood" (in reference to mosquitoes), "fallow moon," and "thunder moon."