Cooler, Less Windy Weather on the Way

Much cooler, damper and less windy weather is expected for the next week, dramatically reducing the fire danger.

If that happens, “it’s going to give us the break we need,” said Inspector Roland Sprewell of the Los Angeles County Fire Department. “Now we can hammer the nails into the coffins of these fires.”

The National Weather Service’s warning of hot, dry, windy and very dangerous fire weather on Monday was replaced by an advisory that no hazardous weather is expected today through the weekend.

High temperatures in some of the fire areas are expected to plummet as much as 25 degrees by Saturday, with Monday’s top readings in the 90s replaced by high temperatures in the upper 60s and low 70s.

Hot, dry Santa Ana winds that gusted up to 50 mph from Friday through Monday will be replaced by gentle, moisture-laden ocean breezes by this afternoon, the weather service said. In many cases, these breezes will flow in the opposite direction of the Santa Anas, helping push flames back over areas that already have burned. Relative humidity, which plummeted to parching levels below 10% during the Santa Anas, will rise to comfortable levels by this afternoon, forecasters said.

And fire officials said the vast clouds of gritty, eye-burning smoke, uncomfortable for all and dangerous for people with respiratory afflictions such as asthma and emphysema, should begin to clear away today as firefighters start gaining the upper hand against the widespread blazes.

Dr. Jonathan Fielding, director of the Los Angeles County Department of Health Services, said that until the smoke clears, residents in fire areas should avoid strenuous exercise and remain indoors whenever possible. Breathing through a damp cloth can reduce the risk when the smoke is heavy.

The Santa Anas are the product of a vast dome of high pressure that parked over the Great Basin area of northeastern Nevada through Monday. Air circulating clockwise around the dome swept southwest across the deserts, over the mountains and into Southern California’s coastal valleys, heating and drying out by compression as it whipped down canyons toward the sea.

Forecasters said that by early today, a trough of low pressure should start nudging this dome to the east. The dry offshore winds should be replaced by damp onshore breezes, with patchy low clouds and fog expected in the coastal valleys of Los Angeles, Ventura and Orange counties by Wednesday.

High temperatures in the coastal valleys should mostly be in the upper 80s today, the upper 70s on Wednesday and Thursday and the upper 60s and low 70s over the weekend. Overnight lows in the coastal mountains should drop well below freezing by the weekend.

The weather service said a series of low-pressure systems should keep the weather cool through much of next week. Forecasters said more Santa Anas are possible over the next three months, but for now, none are in sight.

Late October often marks the beginning of Southern California’s rainy season, but there is no rain in sight, either. Rain is a mixed blessing after wildfires. Gentle rains can snuff out embers and prepare soil for regrowth of burned vegetation, but denuded hillsides are vulnerable to mudslides if the rain is heavy.