A reinforcing west-northwest swell continues to pump large surf for most islands as cloudy weather today heralds the return of tradewinds and also wet weather.

A high surf advisory for north and west shores of Hawaiian isles from Niihau to Maui remains in effect through 6 a.m. Saturday.

The National Weather Service expects the west-northwest swells to keep advisory-level surf along those shores into early Saturday, and says it may possibly continue through Saturday for north shores.

A downward trend, however, is expected over the weekend.

Surf of 12 to 18 feet is expected today along north and west shores of Niihau, Kauai, and north shores of Oahu, Molokai and Maui. Surf of 10 to 14 feet is expected today along west shores of Oahu and Molokai.

Officials warn of strong, breaking waves and rip currents, making swimming difficult and dangerous. Beachgoers, swimmers and surfers should exercise caution, and heed all advice given by ocean safety officials.

Today is expected to be mostly cloudy, with scattered showers throughout the day and highs from 78 to 83 degrees Fahrenheit. Lights winds from early this morning will increase to 10 to 20 mph by this afternoon. Lows tonight range from 64 to 69 degrees.

Forecasters say trades will return today ahead of a cold front moving in from the northwest, which will bring wet and cloudy weather over Kauai this evening, then make its way down the isle chain through Saturday.

An upper-level low is expected to move in from the north Saturday, producing additional showers and isolated thunderstorms this weekend, particularly for windward and mauka areas. The wet weather pattern may continue through Sunday.

A small-boat advisory also remains in effect for most isle waters through 6 a.m. Saturday.