Dozens of fires that devastated large areas in both countries have been controlled, officials say, without revealing the full extent of the damage.
Three people killed in Syria's Latakia province, and some 100 fires burn land across neighbouring Lebanon, officials say.
The wildfires have affected more than 600 families but no fatalities have been reported so far.
California's previous record burn area was nearly 2 million acres in 2018 when the state had its most deadly wildfire that killed at least 85 civilians and destroyed nearly 19,000 structures in and around the mountain town of Paradise.
More than 2,500 firefighters are battling the Glass fire near the resort community of Calistoga, which has already destroyed 248 structures.
"We don't have those critical burning conditions that we were experiencing those last two nights," he said of Glass Fire raging through Napa and Sonoma counties in western US.
US Democratic challenger Joe Biden assails Trump as a "climate arsonist" whose reelection would be catastrophic for the environment.
Search and rescue teams, with dogs in tow, were deployed across the blackened ruins of southern Oregon towns as smoldering wildfires ravaged US Pacific Coast states after causing widespread destruction.
The skies across California have turned dark and orange despite it being daytime –– due to the wildfires, as if in a dystopian film no one wants any part of.
Uncontrolled wildfires rage across US West, incinerating town of Malden and threatening communities in Oregon and California, powered by high winds and unprecedented heat.
Latest fire caused by a couple's plan to reveal their baby's gender when the device they used sparked a wildfire that burned thousands of acres and forced people to flee from a city east of Los Angeles.
Firefighters are for nearly a week battling three huge complexes of fires that destroyed hundreds of homes and forced tens of thousands to flee.
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