The National Weather Service has issued a high surf warning for the north shores of most isles from Niihau to Hawaii island, in effect through 6 p.m. today.

Forecasters say a large north-northwest swell is arriving today.

Surf will build to 20 to 25 feet along affected shores. Strong, breaking waves and currents will make swimming dangerous.

Southwest winds driven by a cold front, according to forecasters, are expected to become breezy and gusty, especially over and downwind of terrain. Showers are expected to increase mainly over the eastern end of the island chain.

A high wind warning is currently in place for the Big Isle summits and Haleakala on Maui through 6 p.m. Wednesday while a wind advisory is in effect through midnight tonight for Kauai County, Oahu, Molokai, Lanai, Maui and Hawaii island.

Southwest winds of 50 to 70 mph on Big Isle summits are expected to increase to 60 to 80 mph today. At Haleakala, southwest winds are expected to build to 50 to 60 mph today. Southwest winds are expected to increase to 20 to 30 mph with localized gusts over 50 mph.

Officials advise postponing travel to the summits until conditions improve.

A small craft advisory is also in place for most isle waters through 6 a.m. Thursday.