Fire Spread, Intensity, and Emissions Observations by Multiple Satellites: The Southern California Wildfires of January 2025

Abstract In January 2025, wildfires caused catastrophic impacts to the infrastructure, communities, and environment of Los Angeles. This study documents the remotely sensed fire spread, intensity, and smoke emissions from the wildfires by leveraging fire and emission observations from multiple satellites. We found that during the first 24 hr after ignition, two main fires moved through urban settlements, under hurricane‐like Santa Ana winds, at rates of up to 3.7 km hr −1 while burning 75%–80% of the final fire areas, including all affected residential areas. We also report the first satellite‐derived intensities of wildfires burning through residential areas. With a mean intensity of 72–297 W m −2 , these fires at night were significantly more intense than the contemporaneous vegetation fires in the Palisades Fire. Smoke emissions exhibited strong hourly variations that were closely coupled with temporal fire intensity patterns, and the emission coefficients (Ce) of carbon monoxide (CO), total particulate matter, and nitrogen oxides (NO x ) were 146, 10.2–21.1, and 0.89 g MJ −1 , respectively. In comparison between vegetation fires and residential‐area fires, CO Ce discrepancies suggest that residential fires likely released less CO emissions per unit of radiative energy, whereas temporal variations in NO x Ce discrepancies varied temporally indicate complex factors influencing Ce in wildfires occurring at the wildland‐Urban Interface. Our findings reveal the extreme characteristics of the Los Angeles wildfires and illustrate how integrated remote sensing imagery can provide critical wildfire information to support safe evacuation, firefighting operations, and air quality forecasting.