Wildfires rage in California

California is no stranger to wildfires, though this event is extraordinary in that it is impacting one of the largest cities in the United States. 

The National Weather Service in Los Angeles has a high-end Red Flag warning in effect through Friday morning (10 January) local time for parts of Los Angeles and Ventura counties. It says due to strong winds there will be increased risk of rapid fire spread and extreme fire behaviour in some areas. In some parts of Los Angelese, however, winds are weakening. 

The fires started on 7 January and spread rapidly. At least 10 people were reported dead and more than 10,000 structures were destroyed. More than 175,000 people were under evacuation orders.  

Last year's rainy season for the Los Angeles area was above normal, and this allowed vegetation to grow large and strong. This was followed by a very dry spell from the end of the rainy season up until the present time, which meant that the relatively large vegetation got tinder-dry, which provided abundant fuel for fires to consume.

Together with the strong Santa Ana winds, which are typical for California, this provided the elements for the perfect storm. The Santa Ana Winds are high winds from the mountains that cause temperatures to rise and cause very low humidity, drying out the ground and vegetation.

The fires were so fierce that the smoke could be seen by satellites from space. 

The fires had a major impact on air quality and public health. Wildfire smoke is a mixure of air pollutants, one of which is particulate matter, which leads to a significant public health threat. This has been the subject of WMO’s annual Air Quality and Climate Bulletin.

The role of climate change

According to the US National Oceanic and Atmospheric Administration (NOAA):

“Climate change, including increased heat, extended drought, and a thirsty atmosphere, has been a key driver in increasing the risk and extent of wildfires in the western United States during the last two decades. 

Wildfires require the alignment of a number of factors, including temperature, humidity, and the lack of moisture in fuels, such as trees, shrubs, grasses, and forest debris. All these factors have strong direct or indirect ties to climate variability and climate change.

A 2016 study found climate change enhanced the drying of organic matter and doubled the number of large fires between 1984 and 2015 in the western United States. A 2021 study supported by NOAA concluded that climate change has been the main driver of the increase in fire weather in the western United States.

The United States had its warmest year on record in 2024, according NOAA.

Other factors:
Land management and prevention - regular clearing of underbrush - play a key role in fire management, and evacuation plans are important in saving lives.
These are all part of effective early warning systems, which WMO is championing through Early Warnings For All.