An El Nino-related tropical storm intensified overnight southwest of Hawaii and could bring a small swell to south shores starting Sunday into next week.

Tropical Storm Pali was packing of 65 mph about 1,375 miles southwest of Honolulu as of 5 p.m. today, the Central Pacific Hurricane Center said. It is not near land.

Pali is slowly moving northwest at 5 mph. It’s expected to weaken over the next three to five days, said Kevin Kodama, a hurricane forecaster with the center.

Warm ocean temperatures near the equator caused the storm to form, he said.

Pali is only the third tropical storm to form in the Central Pacific in January.

The last January tropical storm in the central Pacific Ocean was in 1992, when there was a significant El Nino, Kodama said. The other was in 1989.

El Nino is the natural warming of the central Pacific that interacts with the atmosphere and changes weather worldwide. It occurs every two to seven years or so.

Pali’s formation continues a pattern dating to 2014 of many storms forming in the central Pacific, said Jeff Masters, a former hurricane hunter meteorologist and meteorology director of the private Weather Underground.

That year Tropical Storm Iselle hit the Big Island and two other hurricanes came within 200 miles of the islands. Then last year, eight named storms formed in the central Pacific. That broke the previous record of four set in 1982.

The current El Nino has tied 1997-1998 as the strongest on record, the National Oceanic and Atmospheric Administration’s Climate Prediction Center said, citing statistics that go back to 1950.

This week, days of powerful El Nino-driven storms drenched California and other areas, stopping cable cars in San Francisco, stranding motorists and dumping heavy snow in northern Arizona.

El Nino is closely associated with heavy rain in California, and general warming. It has less of an effect farther away in Europe. With its flipside, La Nina, it is known as the El Nino Southern Oscillation, and it lasts about a year.