Wildfires in California linked to storms in the Indian Ocean

Bursts of convection sweeping eastward across the Indian Ocean and western Pacific keep time with sub-seasonal spikes in wildfires. From California to Korea, these bursts create dry, windy windows in which flames can race unchecked.

A recent study led by Professor Young-Min Yang of Jeonbuk National University is the first to quantify how the Madden–Julian Oscillation (MJO) – an immense 20- to 100-day tropical wave – modulates wildfire activity on a planetary scale.

The international team combined 21 years of satellite fire-emission records, fire-weather indices, and re-analysis data. The study revealed that up to one-fifth of all mid-latitude wildfire events emerge during particular MJO phases.

Tropical storms and Santa Ana winds

When the oscillation’s stormy core clusters over the eastern Indian Ocean, its upper-tropospheric divergence launches a train of Rossby waves that reaches North America and East Asia within a week.

The ocean waves carve high-pressure ridges, lower humidity and quicken surface winds – textbook conditions for fast-moving wildfires.

“Our findings show that strong MJO activity in the eastern Indian Ocean can trigger atmospheric teleconnections, leading to dry and windy weather in wildfire-prone areas like Los Angeles within days to a week,” Yang said. “This provides a crucial prediction window that could improve wildfire forecasting and risk management.”

The same mechanism reverses when deep convection slides into the western Pacific. It flips moisture and wind patterns, altering fire potential.

California, the southeastern United States, East Asia, and eastern Australia all showed alternating pulses. These pulses of enhanced and suppressed fire emissions that marched in step with the eight-phase MJO life cycle.

On average, MJO-linked fire events contributed ten to twenty percent of seasonal burn totals in these regions.

Record-breaking fires in Los Angeles

The study also implicates the Arctic Oscillation (AO). A strongly positive AO phase can funnel cold, desiccating air into mid-latitude corridors, tightening the vise that the MJO sets in motion.

The interplay may help explain why Los Angeles experienced record-breaking winter wildfires in January 2025 despite less severe long-term drought. It may also expound on why South Korea suffered its deadliest blaze on record earlier the same month.

Yang watched the flames claim twenty-eight lives in his home country. He stresses the stakes: large-scale climate modes are now colliding with a warmer, more combustible world, boosting boreal spring and summer fire activities in many tropical and mid-latitude regions.

Oceans can impact wildfires globally

To probe the mechanics, the researchers filtered daily fire-emission data with a 20- to 100-day band-pass. Researchers then compared it to the Canadian Fire Weather Index (FWI).

In the southern United States, East Asia and eastern Europe, correlations between MJO-day FWI anomalies and fire output soared above 0.6. During non-MJO days they barely topped 0.3.

One notable case study traced the August 2020 Complex Fire in northern California – at the time the state’s largest – to a surge in FWI that arrived as Rossby waves arced in from an active Indian Ocean MJO phase. Another study linked the deadly 2010 Russian wildfires to a similar chain of events from the Indian Ocean.

Small-scale tests confirmed the physical underpinnings. In situ atmospheric soundings showed relative-humidity drops of up to 40 percentage points and wind-speed jumps of three to five meters per second during the high-risk phases.

According to the experts, extreme meteorological conditions, with a potential influence from the MJO through atmospheric teleconnections, drove the 2025 Los Angeles fires.

Wildfire and ocean AI prediction models

Existing numerical models already predict the Madden-Julian Oscillation two to four weeks in advance. Yang’s group is weaving those forecasts into machine-learning fire models – alongside signals from the warming tropical Indian Ocean and from Siberian heat anomalies – to flag fire-weather windows up to a month ahead.

“Our ultimate goal is to develop more reliable wildfire prediction models by incorporating MJO and AO influences,” Yang said. Because people and fuel conditions still matter, the authors note that MJO teleconnections are triggers rather than sole causes.

Yet the added lead time could let utilities pre-position crews, help agencies schedule prescribed burns, and guide communities in high-risk corridors to tighten defensible space before Santa Ana winds or East Asian föhn events ignite embers.

A changing baseline for the climate

Climate projections suggest the warm-pool oceans that energize the MJO will continue to expand. If, as some modeling ocean studies indicate, that expansion strengthens the oscillation’s teleconnections, the share of wildfires paced by the MJO could rise.

The study therefore urges wildfire managers to incorporate global climate dynamics into regional plans, warning that local fire weather cannot be fully understood without its tropical heartbeat.

Wildfires may ignite on the ground, but their timing is often written in the sky. By decoding the rhythm linking equatorial thunderstorms to distant dry winds, Yang and colleagues have provided a new key for living with fires on a warming planet.

The study is published in the journal Advances in Atmospheric Sciences.

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