June Gloom

June Gloom is a mainly Southern California term for a weather pattern that results in cloudy, overcast skies with cool temperatures during the late spring and early summer.

June Gloom usually clears up between mid-morning and early afternoon, depending on the strength of the marine layer and the distance of the location from the Pacific Ocean, and gives way to sunny skies.

The clouds, which are formed by the marine layer, move in at night, usually after midnight, and typically dissipate in the late morning, giving way to clear, sunny skies.

During a heavy June Gloom season, the condition may persist into the afternoon, or even all day during an exceptionally strong event.

It is not uncommon for motorists to drive over the Sepulveda Pass from the clear, sunny San Fernando Valley and plunge into a cloudy, fog-filled Los Angeles.

[2] Years with warmer ocean temperatures, referred to as El Niño, may result in fewer gray days in May and June.

June Gloom has been reported by some Californians to bring on symptoms consistent with seasonal affective disorder, although this is not well-supported by evidence.

[14] However, the normally-very-sunny Los Angeles climate also is home to people who thrive during the brief seasonal respite the gloom provides from the unending sunshine and clear skies.

The negative effects of a long June Gloom on the coastal California tourism industry is often reported in the local news media.

[14] The phenomenon can be especially disorienting to visitors from inland areas who, coming from the summer heat, would not expect cool temperatures and clouds and fog at the beach.

[1] The sheet-like stratus clouds are almost uniformly horizontal, covering large areas but having relatively shallow depth of 500 to 2,000 metres (1,600 to 6,600 ft).

A strong low pressure system passing over southern California will produce the deepest and most extensive June Gloom marine layer.

While many parts of the world commonly have an offshore marine layer of stratus or stratocumulus clouds, other locations matching the daily and seasonal effects of Southern California's June Gloom are relatively rare.