What Tuesday’s weather means for viewing Fourth of July fireworks across San Diego County

Forecasters say clouds might form over the coast, but they won’t be low enough to prevent the public from seeing the fireworks.
The skies won’t be as clear as forecasters initially expected along the coast, but the National Weather Service says that Tuesday’s Fourth of July fireworks should still be vibrant in most areas.
The high pressure system that brought fair weather over the weekend will greatly weaken by Tuesday, allowing clouds to form during the afternoon and drift toward shore.
From the Big Bay Boom and other firework shows to parades and ceremonies, here’s how to celebrate the Fourth of July in San Diego County
“The clouds could become really widespread at the coast, and very low, maybe with bases of only 700 feet or so,” said James Brotherton, a weather service forecaster. “That could cause smoke from the fireworks to disperse more slowly.”
Most fireworks explode less than 500 feet in the atmosphere.
Inland skies should be mostly clear.
The wind is expected to blow from the northwest at 7 to 8 mph in most areas. That’s not strong enough to fully disperse smoke near the ground. But it also means that the winds won’t widely spread firework embers that can cause brush fires, the weather service said.
The evening humidity along the coast will be about 75 percent. If it gets substantially higher it could reduce the brightness of some fireworks. But that scenario doesn’t appear likely, partly because the region isn’t experiencing the sort of monsoonal moisture that raises the humidity to very high levels for prolonged periods of time.
The absence of the monsoon also means that the county won’t experience lightning on a night when huge numbers of people will be outside.
There’s one other factor that will make for good viewing. A nearly full moon will rise above the southeast horizon Tuesday night. But it won’t begin to appear until almost 10 p.m., by which time most fireworks shows will be over. If it occurred earlier, the moon’s reflected light would reduce the vibrancy of some fireworks.