San Diego's warmest weather of the year (on average), ocean water temperatures peak, brilliant Venus, and a full moon
San Diego's warmest weather, on average, should occur in August through early September, according to statistics compiled from several decades of measurements taken near the San Diego International Airport. In an average year, coastal residents enjoy an average daily temperature of 70°, which compares favorably (depending on your viewpoint) with the January average daily temperature of 55°. The range between the high and low is typically 10° or less this time of year. August's warm, semi-tropical weather will eventually give way to September's and October's slightly cooler days interspersed with occasional heat waves brought on by Santa Ana conditions -- dry, hot winds that sweep down the mountain slopes from the interior.
Ocean water temperatures are probably peaking now, the result of many weeks of summer sunshine and warm coastal air temperatures. While the water offshore seldom exceeds 70 degrees F, shallow-water temperatures of 70-80 degrees are not uncommon on gently shelving beaches late in the day. Wide, sandy beaches such as Coronado, south Mission Beach, and La Jolla Shores are likely now at their best for comfortable bathing.
Brilliant Venus, plus the much fainter Saturn and Mercury, lie within a small circle about 3 degrees across on the evenings of August 14, 15 and 16. Look low in the west around 1/2 hour after the sun sets. Binoculars will likely be needed to see Saturn and possibly Mercury. Reddish Mars lies to the upper left of the tight group of three. The four planets in the west will set quickly, but Jupiter, an unblinking beacon in the east at nightfall, will remain in the sky nearly all night.
August's full moon rises impressively from the east horizon at around 7:35 p.m., about 10 minutes after the time of sunset, on Saturday, August 16. Some folk names for the August full moon include "corn moon," "barley moon," and "moon when cherries turn black" -- in reference to an agricultural heritage of more northern climes than San Diego.