Kevin Van Leer, senior product manager – Model Product Management, RMS
20:00 UTC Tuesday, October 17
Nearly ten days have passed since the first four wildfires spread rapidly in Northern California. As of Monday, October 16, over 10,000 firefighters battled 14 fires, principally in the wine-growing valleys north of San Francisco. Fires in Napa, Solano, Sonoma, Mendocino, Lake, Yuba, Butte, Fresno, Calveras, Orange and Nevada counties have burned about 213,000 acres (86,000 hectares), destroying about 5,700 structures and forcing the evacuation of over 100,000 people, according to CAL FIRE and local officials. Aerial photographs show whole neighborhoods in northern Santa Rosa destroyed, and a neighborhood of about 70 houses has been destroyed in east Santa Rosa. Reports on Monday, October 16 state that there are 41 recorded fatalities, and hundreds of people are missing.

Figure 1: RMS fire perimeters derived using satellite imagery and local information. The 2015 Valley Fire Perimeter is shown for comparison.
RMS generates estimates of burn perimeters using satellite imagery, such as from the Visible Infrared Imaging Radiometer Suite (VIIRS) operated by the U.S. Department of Agriculture. This near real-time imagery detects burning fires using spectral temperature comparisons against the surroundings.
Using this in-house high-resolution exposure information and the satellite derived perimeters for the fires impacting Napa, Sonoma, Solano, Lake, and Mendocino counties, RMS analysis calculates that the perimeters include approximately 17,000 structures and US$14.8 billion in total exposure. The table below provides a breakdown of the impacted exposure. It is important to note that not all structures within the perimeters will be damaged. The 5,041 structures reportedly destroyed in these fires as of today Tuesday, October 17, is in line with RMS historical event research into the fraction of structures within a perimeter that are either damaged or destroyed.

Based on the perimeters for these fires representative of the information available at the time of this post on Tuesday, October 17, RMS estimates an economic loss range between US$3 billion and US$6 billion. This range is not inclusive of fires outside of these counties, which have impacted an additional 600+ structures combined.
Because of the high penetration rate of wildfire coverage in standard residential and non-residential policies, this range also represents an estimate of insured losses. The range includes loss due to property damage, contents and business interruption caused by the burn component of the fires to residential, commercial, and industrial lines of business. It does not include automobile or agricultural crop losses, smoke damage, or any factor for post-loss amplification. Because of the impacts to the wine industry throughout the region, RMS notes the significant uncertainty regarding the long-term business interruption for this event, which could result in a higher total loss.
It is important to note that these events are still ongoing and the perimeters of the active fires may change significantly before final containment. Therefore, this exposure and loss estimate are considered preliminary and are representative of the current situation. RMS will continue to provide updates on this event through RMS Owl.