Meteorology demonstrate that Los Angeles wildfires were intensified by strong winds and dry conditions
What started as a warning about a small fire in the Santa Monica Mountains, 60 km from the famous Hollywood Hills, ended up making history as a chain of fires comparable to the most catastrophic in California’s history.
The following analysis will examine various meteorological components (parameters) to understand how weather conditions have influenced both the origin and the unstoppable spread of the flames toward the city, as well as their consequences.
Satellite image from January 9, 2025, showing active wildfires around Los Angeles
Source: Sentinel 3 (ESA)
Smoke dispersion from the fires between 18:00 and 23:56 UTC on January 9, 2025
Source: GOES-18 Satellite (NOAA)
Favorable conditions (drought)
The state of California has experienced widespread drought over the past decade, with the exception of the anomalously wet years of 2022 and 2023, when regional vegetation saw a significant increase. However, there has been no recorded rainfall in Los Angeles since last October, causing this vegetation to dry out and create a substantial amount of fuel for potential wildfires.
This points to climate change as a key factor, as it is responsible for the abrupt alternation between dry and wet periods, both increasing the destructive potential of these events and shifting their temporal distribution. Significant wildfires had never been recorded in this region during January before; summer has traditionally been the season when fires typically begin.
Monthly temporal distribution of wildfires in California as of January 13, 2025
Source: The Economist
Winds
The Santa Ana winds are well known in Southern California and the Los Angeles metropolitan area. These katabatic winds, originating from the northeast and therefore from the continent, descend from the mountains, accelerating, warming, and losing humidity due to the Foehn effect.
At the onset of the first flames, Santa Ana winds rapidly intensified from 90 km/h to gusts of 160 km/h, which spread the fire at a tremendous speed.
Wind pattern in Southern California on January 8, 2025
Source: earth.nullschool.net
Air quality
Los Angeles is one of the cities most affected by air quality issues. Its geography—a flat terrain between the coast and a mountain range—creates air recirculation, meaning that the air does not renew and remains trapped over the city. As a result, the accumulation of smoke and airborne particles from the wildfires further deteriorates the already poor air quality.
Topography of the Los Angeles basin with mountain systems that trap air over the city
Source: ASTER Data (NASA)
The alternating drought and rainfall patterns caused by climate change, combined with the unique wind patterns and geography of Los Angeles and the surrounding mountainous terrain, make this region particularly susceptible to extreme events like the one witnessed at the start of 2025. Given the potential for these events to become recurrent, studying meteorology and its variations is crucial for predicting and mitigating their effects.
