A high surf advisory has been issued for the north and west shores of all islands in Hawaii, effective through 6 p.m. today due to a northwest swell.

The National Weather Service says surf of 12 to 16 feet is expected along north shores of Niihau, Kauai, Oahu, Molokai and Maui. Surf of 8 to 12 feet is expected along west shores of Niihau, Kauai, Oahu and Molokai.

Surf of 5 to 8 feet, meanwhile, is expected along west shores of the Big Island.

Officials warn of strong, breaking waves and strong rip currents, making swimming difficult and dangerous.

Lifeguards in Ala Moana and Waikiki are also reporting a large influx of box jellyfish along the shoreline. The jellyfish can cause painful stings and allergic and medical reactions, so the public should use extreme caution when entering these waters. Warning signs have been posted.

A brown water advisory has also been issued at Waimea Bay and Punaluu Beach Park on Oahu due to rains resulting in stormwater runoff entering coastal waters. The public is advised to stay out of if the water is brown.

Officials also remind the public that all beach parks on Oahu are closed and that no sitting, lying, sunbathing or congregating on beaches is advised due to Mayor Kirk Honolulu’s “stay-at-home/work-from-home” order.

Tradewinds have returned due to a high-pressure ridge north of the isles, and moderate trades will continue, along with stable, mostly dry weather conditions through Saturday.

A cold front, however, will approach the isles on Sunday and will once again weaken the ridge, diminishing the trades.

Today will be mostly sunny, with isolated afternoon showers, highs from 79 to 84 degrees Fahrenheit, and trades from 10 to 20 mph. Tonight will be partly cloudy, with isolated showers after midnight, and lows from 64 to 69 degrees.

The current, northwest swell should decline through Friday, forecasters said, but will be reinforced by additional pulses from the northwest during the weekend and middle of next week.

North Shore surf will likely reach advisory levels when the swells peak late Saturday and Sunday and possibly Wednesday. Surf along east shores, meanwhile, will remain near or below normal, April levels for the next few days.