El Nino in 1997 and 2015
Satellite images comparing 1 October and 2 October show large areas of white, which indicate high sea levels – a reflection of high sea temperatures. The images show this year's El Niño could be the most powerful since 1997. NASA Jet Propulsion Laboratory

This year's El Niño weather system is gaining strength in the Pacific Ocean and is expected to be the second strongest on record, scientists have said. The strengthening meteorological event is likely to cause an extremely wet winter in California with no possibility for it to weaken now.

Scientists have said that El Niño is getting stronger because of a rising sea-level ocean temperature in the Pacific Ocean and a change of wind direction along the equator, which allows the warm water to move towards the Americas. This means that the winter storms that normally witnessed in Central America could move further north over California and the southern US.

"There's no longer a possibility that El Niño wimps out at this point," said Bill Patzert, climatologist for Nasa's Jet Propulsion Laboratory in La Cañada Flintridge. "And the winter over North America is definitely not going to be normal."

Southern California now has a more than 60% chance of getting a wet winter, with only a 7% chance of a dry one. The odds of a wet winter for places further north are increasing too, with San Francisco having a more than 40% chance.

"The ocean has warmed up a little bit more," said Mike Halpert, deputy director of the Climate Prediction Center. "It's certainly still a strong event. Probably the second strongest we've seen at this time of year."

The strongest El Niño on record developed in 1997, with heavy rains reaching seven inches in Orange County in the winter. Rains in Los Angeles County at the time were the worst across the region, with downtown Los Angeles getting a year's worth of rain in February alone. Flooding and mudslides destroyed many houses and killed residents in Laguna Beach and more than $500,000,000 ($326,232,000) in damages was reported in California, where 17 people died.

On the other side of the Atlantic Ocean forecasters have warned that Britain could be facing its coldest winter in 50 years as a result of the El Niño. Some reports indicated that the country could face a repeat of 1963, when the worst winter in history saw temperatures drop to -20C, causing the River Thames to freeze.