California has spent years learning what it means to live without enough water. Reservoirs, farms, forests and communities have all felt the pressure of drought, making the arrival of winter rain something many Californians will welcome.
But this year, the anticipation comes with another question.
What happens if the rain California needs arrives with enough force to create a different kind of danger?
A very strong El Niño is developing in the Pacific, and federal forecasters expect wetter-than-average conditions across much of the southern United States this winter, including California.
The forecast does not mean every part of the state will flood, or that a particular storm can be predicted months in advance, but it has prompted California officials to prepare for the possibility of repeated heavy storms, flooding, landslides, debris flows and coastal impacts.
For California, the coming months could therefore bring an uncomfortable contradiction: the state can need the rain and still fear what too much of it could do.
California wants the water, but winter could bring a different challenge
California's water year began on October 1, and state water managers are already positioning the state to capture as much precipitation as possible.
The California Department of Water Resources says major reservoirs were at about 107% of their historical average for that date, although Lake Oroville, the largest reservoir in the State Water Project, was at 85% of average and 48% of capacity. The state is preparing to use both surface reservoirs and groundwater basins to capture winter precipitation that could become valuable when dry conditions return.
California does not simply want to keep storms away. It wants to make use of the water.
At the same time, officials know that intense rainfall can overwhelm roads, drainage systems, rivers and hillsides, particularly when several hazards arrive together.
Tom Gibson, director of the California Department of Water Resources, put the challenge plainly as the new water year began.
“We don’t yet know where or when the storms will hit, but we can take actions to prepare now.”
The state has already stockpiled 4.4 million sandbags and 400,000 tons of rock for emergency flood-control work at locations around California. Officials are also inspecting the state's flood infrastructure ahead of the winter season.
Then there is El Niño
El Niño is a natural climate pattern involving unusually warm sea-surface temperatures in the tropical Pacific.
Its effects can extend far beyond the Pacific, influencing the position of the jet stream and changing the odds of certain types of weather across different parts of the United States. NOAA's October 15 winter outlook says a strong El Niño is expected to influence the coming December-to-February season, with wetter-than-average conditions favored across the southern United States, from California to Florida.
For California, however, a forecast is not a promise.
Michael Anderson, California's state climatologist, stressed that distinction in a statement from the Department of Water Resources.
“Historically, El Niño years can be a mixed bag, with moderately higher chances of more precipitation in the southern part of the state.”
He added that the strength of this year's event creates conditions favorable for wet weather, while emphasizing the importance of following local forecasts and National Weather Service warnings.
In other words, El Niño can tilt the odds.
It cannot tell a family exactly which day their neighborhood will flood.
Fire and rain can become part of the same story
California's relationship with wildfire has already changed the way many residents think about the seasons.
The traditional idea of a fire season followed by a rainy season is becoming harder to treat as a simple sequence. Hot, dry conditions can leave vegetation stressed and increase wildfire danger, while the storms that eventually bring relief can create new hazards on landscapes that have recently burned.
California officials are preparing for that possibility.
The state's Department of Water Resources says it is coordinating flood preparedness with local agencies and monitoring areas where wildfire has increased the potential for debris flows. The National Weather Service also maintains specific burn-scar information and rainfall thresholds for vulnerable areas.
The science does not say every rainstorm after a wildfire will produce a landslide.
It says the risk can be higher under the right combination of rainfall, slope, soil and burn conditions.
That distinction matters.
The climate change question is more complicated
It would be tempting to connect every part of this story directly to climate change.
The evidence does not support such a simple explanation.
El Niño is a natural climate phenomenon, and California's storms, droughts and wildfires have many causes. A particular storm cannot simply be labelled a product of climate change because it happens during a warming period.
But climate change is altering the background conditions in which these events occur.
A warmer climate can contribute to hotter and drier conditions that increase wildfire risk, while warmer oceans and rising sea levels can influence coastal hazards. Scientists are also studying how a warming atmosphere affects extreme precipitation and how different hazards can compound one another.
That means California's climate challenge is not necessarily about choosing between drought and floods.
It may increasingly be about preparing for both.
What Happens Next
The coming weeks will reveal how closely reality follows the seasonal forecasts.
NOAA says the odds favor a wetter winter across much of the southern United States, while California officials are preparing for the possibility of strong storms and their associated hazards. But the precise location, timing and intensity of individual storms cannot yet be known.
That uncertainty is why officials are preparing before the first major winter storm arrives.
For Californians, the message is not to fear the rain.
It is to understand it.
A storm can replenish a reservoir, revive dry ground and add desperately needed water to the state's supplies. The same storm can also flood a road, send debris down a burned hillside or batter an already vulnerable coastline.
California has spent decades learning how to live with too little water.
Now, as a powerful El Niño develops, the state is preparing for the possibility that its next challenge could be learning how to safely handle the water when it finally comes.
Because sometimes the weather people have been waiting for is also the weather they have to prepare for.
