A natural warming cycle is called El Niño.

It is heating Pacific Ocean waters.

It adds water to the air.

This water can feed passing storms.

El Niño events happen every few years.

But scientists say this one is very strong.

Meteorologist Jeff Masters works at Yale Climate Connections.

He called it a "super duper El Niño."

Scientists say this strong El Niño makes heavy rain more likely.

The rain is also stronger across the Southern U.S.

The effects are stronger in desert areas.

The land there does not take in water well.

On Sunday, flash floods led to evacuations.

This happened across northern New Mexico and central Arizona.

A ski town in Colorado got ready for its main river to rise.

The river could reach very bad levels.

The week before, another storm brought days of floods.

This hit southwestern states.

Over 20 trillion gallons of water fell on the Four Corners states and Nevada.

This happened in the past two weeks.

Ryan Maue said this.

He was chief scientist at NOAA.

Experts say El Niño adds water to the air.

It also moves wind patterns.

This pushes strong air currents toward the Southwest.

There they can mix up that water.

Climate scientist Daniel Swain works at the University of California Agriculture and Natural Resources.

He said big rain in the Southwest interior is more likely this time of year.

But he said it is happening more than before.

Meteorologist Randy Cerveny works at Arizona State University.

He said warmer ocean temperatures make these El Niño events stronger.

Human-caused climate change is part of the cause.

Experts expect the El Niño to peak in December.

Then it can pull jet streams more strongly.

It can make more extreme storms across the western U.S.

Experts say its effects could last for months.

Park Williams works at UC San Diego's Scripps Institution of Oceanography.

He said in an email that more heavy storms are likely this winter and spring.

Cerveny said the effects are not all bad.

El Niño can bring rain to dry areas.

It can fill reservoirs.

But storms and floods can put people and property in danger.

Experts said to watch the forecast.

They said to plan ahead.

They said to listen to evacuation warnings.