A high surf advisory has been issued for the north and west shores of isles from Niihau to Maui, effective through 6 p.m. Friday.

The National Weather Service says a significant, northwest swell will build today and tonight, with an additional reinforcement on Thursday, which will produce dangerously, large surf through Friday.

Surf of 15 to 20 feet is expected along the north and west shores of Niihau and Kauai, and north shores of Oahu, Molokai and Maui. Surf of 10 to 14 feet is expected along the west shores of Oahu and Molokai.

Officials warn of strong, breaking waves and rip currents, making swimming difficult and dangerous and entering the water very hazardous. Swimmers and surfers should exercise caution and heed all advice given by ocean safety officials.

Tradewinds, meanwhile, are expected to make a comeback from the east today and will build into the light to moderate range for all isles by tonight.

Today’s forecast is partly sunny, with isolated showers, and highs from 80 to 85 degrees Fahrenheit. East winds of 10 to 15 mph will remain through tonight when lows range from 67 to 72 degrees.

Forecasters say moderate trades should last through the middle of next week, bringing rains to the windward and mauka side.