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MegafireCalifornia · 2017

Thomas Fire (2017)

December 4, 2017 – January 12, 2018

Acres burned
281,893
Deaths
2
Structures destroyed
1,063
Damage
$2.2B

Fast Facts

Date
December 4, 2017 – January 12, 2018
Acres burned
281,893 — largest CA fire at the time
Counties
Ventura, Santa Barbara
Deaths
2 (1 firefighter direct + 1 civilian)
Mudslide deaths (post-fire)
23 at Montecito on January 9, 2018
Structures destroyed
1,063
Damage
$2.2 billion (2017 USD)
Cause
SCE power line + 2nd ignition

Cause: Southern California Edison power line + 2nd ignition under investigation

Perimeter & Origin Map

Hover or tap markers for details
Ignition point
Impact location
Burn perimeter
Severity: > 100,000 acres

Perimeter is a simplified polygon approximating the final burn footprint from NIFC/CalFire records. Origin coordinates from the official incident investigation report.

A Santa Ana firestorm

The Thomas Fire was driven by one of the most severe Santa Ana wind events of recent decades. Sustained 50 to 70 mph winds with gusts to 85 mph drove the fire from its Anlauf Canyon ignition point northwest into Ventura, with active flames reaching the city's hillside neighborhoods within four hours. By midnight on December 4-5, the fire had grown to over 50,000 acres — an extreme initial-day spread rate. Over the following weeks the fire moved generally west and northwest, repeatedly threatening the cities of Ojai, Carpinteria, and Santa Barbara. Successful structure defense in Ojai during the night of December 8-9 became one of the defining moments of the campaign. The fire was finally fully contained on January 12, 2018, approximately five weeks after ignition.

The Montecito mudslide

On January 9, 2018, an intense Pacific storm dropped approximately one inch of rain in 15 minutes on the steep slopes above Montecito — terrain whose chaparral cover had been completely burned by the Thomas Fire just weeks earlier, eliminating the natural infiltration capacity of the soil. The resulting debris flow swept downslope through Romero Canyon and Cold Spring Canyon in a wall estimated at 15 feet high, picking up boulders the size of cars. Twenty-three people were killed in the debris flow, more than half of them in homes that were swept off their foundations and carried hundreds of yards downslope. Approximately 130 homes were destroyed and 300 more were damaged. The town's primary access road — Highway 101 — was closed for 13 days while the National Guard, Caltrans, and contractors removed approximately 3 million cubic yards of debris.

Frequently Asked Questions

What was the Montecito mudslide?

On January 9, 2018, one month after the Thomas Fire had burned the watershed above Montecito, an intense rainstorm dropped approximately one inch of rain in 15 minutes on the recently denuded slopes of Romero Canyon and Cold Spring Canyon. The resulting debris flow killed 23 people and destroyed approximately 130 homes in Montecito. The mudslide was a direct hydrological consequence of the Thomas Fire and is commonly counted as part of the fire's total casualties.

How big was the Thomas Fire?

The Thomas Fire burned 281,893 acres across Ventura and Santa Barbara Counties between December 4, 2017 and January 12, 2018. At the time it was the largest single wildfire in California's recorded history (a record subsequently broken multiple times, most recently by the August Complex in 2020).

How did the Thomas Fire start?

The CalFire investigation determined that the Thomas Fire was ignited at approximately 6:24 p.m. PST on December 4, 2017 by a Southern California Edison power line failure in Anlauf Canyon, near Steckel Park in Ventura County. A second ignition occurred approximately one mile away that night; investigators determined both ignitions merged within hours. SCE settled approximately $4 billion in fire damage claims in 2020.

Sources

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