California is once again confronting a rapidly escalating wildfire season fuelled by extreme heat, drying vegetation, drought and strong winds. As of 24 July, the state has recorded more than 3,800 wildfires so far this year, burning approximately 79,000 hectares. The largest active blaze, in Lassen County, had grown to more than 28,000 hectares.The immediate images are familiar to Australians: towering smoke columns and orange skies. But these wildfires are not simply the result of hot summer weather. They are driven by a chain of interacting climatic, environmental and human factors. In Australia, a powerful El Niño and the possible emergence of a positive Indian Ocean Dipole would bring drier, warmer weather. This could create similarly dangerous conditions in southern and eastern Australia this spring and summer.A hot, dry landscape primed to burnIn southern California, persistent drought, abundant grass growth and low coastal moisture have accelerated the drying of vegetation. In the north of the state, early–season dryness and the development of “flash drought” conditions have pushed some landscapes towards critical fire danger.As temperatures rise, warm air can draw more moisture from plants and soils. This means that even if it rains, vegetation cannot replace the water it loses. Even living plants can dry enough to burn fiercely.Warm nights — a product of global heating — are another concern. Previously, cool and humid overnight conditions give firefighters a chance to strengthen containment lines. When nights remain hot and dry, fires can burn around the clock. A fire helicopter drops water over flames as crews battle a wildfire named as ‘Little Fire’ in Alameda County, California on July 21, 2026. Tayfun Coskun/Getty Strong winds and a century of fire suppressionHeat and drought create flammable landscapes, but wind often determines whether a fire becomes a disaster. As we witnessed with the catastrophic Los Angeles wildfires in January 2025, California’s mountain ranges, valleys and passes can funnel winds. The significance of wind was clear in the present fires in eastern California, where erratic winds contributed to rapid fire spread around the Highway 395 corridor.California’s rugged terrain also makes wildfires more difficult to control. Flames generally travel faster uphill because heat rises and preheats vegetation above the fire. Steep slopes also restrict access for firefighting vehicles and ground crews.In some forests, decades of fire suppression have contributed to dense undergrowth and accumulations of fallen timber. Frequent, relatively mild fires once removed some of this material. Where wildfire has been excluded, vegetation may form “ladder fuels” that carry flames from the forest floor into the tree canopy.Climate change is loading the diceFires can begin through lightning, machinery, vehicles, power lines, campfires or deliberate acts. Climate change creates a warmer background climate in which fuels dry more quickly and remain dry for longer.The US National Oceanic and Atmospheric Administration reports climate change has become one of the dominant drivers of the increase in fire weather conditions across the western United States. Research has also identified an increase of about 25 days in the annual fire season when dangerous fire conditions occur simultaneously across large areas of the western United States. This raises the possibility of several major fires competing for aircraft, firefighters and emergency resources at the same time.Climate change is loading the dice towards more dangerous fire weather globally, even though weather, ignition and land management still determine the behaviour of individual fires.California’s wildfire risk is also increasing because homes and infrastructure continue to expand into the wildland–urban interface: the zone where towns and suburbs meet forests, grasslands and shrublands.Australia’s warning from across the PacificThe Californian wildfires carry a clear warning for southern and eastern Australia as spring and summer approach.The Bureau of Meteorology confirmed on 14 July that El Niño is underway, with oceanic and atmospheric indicators showing a well–established event. Most climate models indicate that El Niño will strengthen and persist until at least the austral summer, with a high likelihood of becoming a very strong event and potentially ranking among the strongest observed since 1950.El Niño commonly reduces winter and spring rainfall across eastern Australia and is associated with warmer daytime temperatures in southern Australia. Its effects vary between events, however. The strength of an El Niño does not translate directly into the severity of drought or bushfire.Also of interest is the Indian Ocean Dipole (IOD). In mid–July it remained neutral, indicating that sea–surface temperatures across the tropical Indian Ocean were close to their long–term average and that a positive IOD had not yet developed.During a positive IOD, waters near Indonesia and north–western Australia are cooler than normal, while the western tropical Indian Ocean becomes warmer. This tends to shift tropical rainfall westwards and reduce the moisture available to rain–bearing systems across southern and south–eastern Australia.If a strong El Niño and positive IOD develop together, their drying influences could reinforce one another during late winter and spring.How we should respondThe present warning signs are concerning Australian fire and emergency authorities. The seasonal outlook for winter 2026 found above–normal fire potential in drought–affected parts of central and northern New South Wales.Without significant rainfall, warmer and drier conditions could also produce increased fire activity across south-eastern Australia. The greatest danger would arise where earlier rainfall promoted abundant growth of grasses and shrubs. This does not guarantee a severe Australian bushfire season. Nevertheless, the warning signs justify early preparation. California demonstrates how quickly drought, heat, dry fuels, wind and human exposure can combine to produce a major emergency. Should a strong or very strong El Niño coincide with a positive IOD, southern and eastern Australia may enter spring with a highly flammable landscape — and with little room for complacency.Steve Turton has previously received funding from the Australian and Queensland Governments.