A high-surf advisory has been issued for the north- and west-facing shores of Niihau, Kauai, Oahu and Molokai, and the north-facing shores of Maui, effective through 6 a.m. Friday.

A northwest swell will maintain elevated surf along most north- and west-facing shores on these smaller isles through early Friday, according to the National Weather Service.

Surf of 14 to 18 feet is expected along north-facing shores, and of 10 to 14 feet along west-facing shores.

More rains and a few thunderstorms, meanwhile, are possible over the eastern end of the state due to an upper disturbance in the area, according to forecasters.

Today’s forecast for Kauai and Oahu is partly cloudy with showers likely on the windward side, and highs from 80 to 85 degrees Fahrenheit. For Maui and Hawaii island, the forecast is mostly cloudy with numerous showers, some that may be heavy, and isolated thunderstorms, particularly for the windward side.

Lows tonight dip to 67 to 72 degrees as trades ramp up to 15 to 30 mph.

The long-period northwest swell that brought the high surf advisory for north and west facing shores is expected to peak tonight at 14 to 18 feet before lowering to 10 to 14 Friday morning, according to forecasters.

Surf on west-facing shores peaks at 10 to 14 feet tonight before lowering to 7 to 10 feet Friday morning.

Surf on east-facing shores will steadily trend up due to strengthening trades, from 4 to 6 feet today to 5 to 7 feet Friday morning.

Surf on south-facing shores remains steady at 1 to 3 feet today and Friday.

Forecasters expect conditions to improve over the weekend, with breezy trades remaining through Saturday.

A small craft advisory has also been issued for windward Maui County waters, Maalaea Bay, Pailolo and Alenuihaha channels, and most Hawaii island waters, effective through 6 p.m. Saturday.