From the backcountry of Campo to the back roads of Ramona, firefighters were ready to roll last fall at even the hint of wildfire.
Two years of below-average rain and high temperatures had left the landscape parched. Something as small as heat from a car muffler could be enough to ignite grass. Firefighters described the region as primed to burn.
The unexpected followed.
The rainy season that ended on Saturday night was the wettest in nearly 20 years and featured a social media sensation in the form of Hilary, the first tropical storm to make a direct hit on San Diego in more than 80 years.
The 500-mile-wide system methodically moved up the Pacific coast of Mexico and surged into San Diego County on Aug. 20, where it dropped more than 7 inches of rain on Mount Laguna and 1.82 inches on San Diego International Airport, which averages 0.01 inches for the month.
Boulders tumbled onto Interstate 8 near In-Ko-Pah. Swift water rescue crews aided about a dozen people at a homeless camp on the San Diego River near Morena. DoorDash suspended food deliveries. And the Navy felt relief that officials had sent many of its warships out to sea so they wouldn’t get battered at their piers in San Diego Harbor.
Part of the blustery storm then chugged into greater Los Angeles, producing a ring of floodwater around Dodger Stadium that amused Padres fans. Another piece curled east and flooded the Las Vegas Strip.
Hilary contributed to what turned out to be a very impressive amount of precipitation during the so-called rainy season, which lasts from Oct. 1 to Sept. 30 of each year. It’s also referred to as the water year.
The San Diego airport recorded 15.72 inches of rain, which is 5.96 inches above average. The last time San Diego received more precipitation was during the 2004-05 season, when the airport received 22.60 inches, the weather service said.
Oceanside Harbor received 23.47 inches, which is 13.20 inches above average. Escondido logged 29.77 inches, which is 15.25 inches above average. And Ramona got 25.63 inches, which is 10.98 inches above average.
The heaviest rainfall hit Palomar Mountain, which recorded 69.26 inches, or 38.85 inches above average, the weather service added.
Forecasters said that San Diego County got drenched because comparatively few strong high pressure systems appeared and lingered off the Gulf of Alaska and Pacific Northwest, allowing storms to sink into Southern California. The opposite happened during the previous two seasons.
The county also experienced a wet winter because numerous atmospheric rivers developed in the Pacific. The term refers to large plumes of moisture that form in the subtropics and sometimes get drawn into California by North Pacific storms. Their moisture increases the power of many storms.
More than 30 “ARs” developed during rainy season, according to UC San Diego’s Scripps Institution of Oceanography. Many of the plumes affected San Diego County, especially in January, when San Diego got 5.14 inches of rain, more than twice its average rainfall.
The rainy season also was notable for its snowfall. The San Bernardino Mountains northeast of San Diego County got more than 100 inches of snow is less than a week in early March. Far smaller amounts fell in the San Diego mountains. But white-out conditions hit some elevated areas, and the combination of snow and fierce winds made travel on I-8 in eastern San Diego County treacherous and, at times, imable.
Then there was the cold.
Beginning in November, San Diego experienced eight consecutive months of below-average temperatures, something that had not happened since the early 1960s.
And from June 1 through Aug. 31, the city’s daytime high temperature did not rise above 84 degrees.
“That’s unusual,” said Liz Adams, a weather service forecaster. “It usually gets into the 90s. That didn’t happen this year.”
The robust rain and cool temperatures have reduced the risk of wildfires. But Adams’ colleague, Alex Tardy, said this is not a moment for complacency.
“If we got a couple of weeks of strong Santa Ana winds it could really dry out the vegetation across the county,” Tardy said. “We’d lose much of the advantage we’ve had.”
There’s a reason to feel edgy about it. The near-term forecast calls for potentially strong Santa Anas. They’re expected to start blowing on Wednesday.
A lot of people are listening particularly closely to Tardy. He’s the forecaster who correctly predicted, five days in advance, that Hilary would blow directly through San Diego.
Union-Tribune reporter David Hernandez contributed to this story.
