The threat of wildfire hovered over the Southland today because of gusty winds, low humidity, and the possibility of dry lightning, forecasters said. Additionally, the region today faces a 20 percent chance of showers and thunderstorms, according to the National weather service.

A red flag warning indicating a risk of wildfire will be in force until noon in the San Gabriel Mountains and the forests they encapsulate — the Angeles National Forest in Los Angeles County and the Los Padres National Forest in Ventura County.

Weak Santa Ana winds gave way to onshore winds Sunday afternoon, but warm and dry condition nonetheless will persist through this morning, according to a National Weather Service statement.

Once the red flag warning expires, a less serious fire weather watch will go into effect through this evening because of the prospect of dry lightning — lightning strikes that occur when accompanying precipitation dissipates before hitting the ground.

The fire weather watch will apply not just to the San Gabriel mountains, but also to the Santa Monica Mountain Recreational Area, beach cities, metropolitan Los Angeles, and the San Fernando, Santa Clarita, San Gabriel and Antelope valleys.

Along with the onshore winds, which will produce 35-mile-per-hour gusts, the region will experience an influx of subtropical moisture this afternoon and evening, forecasters said. The moisture combined with a low-pressure system

offshore will create a slight chance of thunderstorms through Tuesday evening, with another slight chance of thunderstorms cropping up in the San Gabriels Wednesday afternoon, they said.

“The initial surge of mid-level moisture and instability will bring the greatest threat of isolated dry lightning with gusty erratic winds on Monday afternoon and evening,” the NWS statement said, adding that dry lightning would increase the threat of fire, in part due to the presence of “extremely dry fuels.”

“If fire ignition occurs, conditions are favorable for extreme fire behavior and rapid spread of wildfire, which would threaten life and property.”

But beginning tonight, any storm that develops should be a wet one, forecasters said.

The NWS forecast cloudy skies today and highs of 79 in Avalon; 84 at LAX; 88 in Long Beach; 89 in downtown L.A. and on Mount Wilson; 91 in San Gabriel; 92 in Burbank; 93 in Saugus; 95 in Pasadena and Palmdale; and 97 in Woodland Hills and Lancaster. Highs will be a few degrees lower Tuesday and drop again starting Wednesday but start climbing again Saturday.

In Orange County, a dense fog advisory was in effect until 9 a.m., and cloudy skies were forecast, along with highs of 78 in San Clemente; 79 in Newport Beach; 80 in Laguna Beach; 96 in Anaheim, Irvine and Mission Viejo; 87 in Yorba Linda; and 90 in Yorba Linda. Orange County temperatures will decline slightly starting Tuesday but inch up again starting Saturday. By Sunday, they’ll generally be back at today’s levels.