A high surf warning will take effect for the north- and west-facing shores of Oahu, Kauai, Molokai and Niihau, and for the north-facing shores of Maui.
The warning is from 6 a.m. Wednesday to 6 p.m. Thursday.
The National Weather Service reported that a northwest swell is expected to build overnight into Wednesday morning, peak Wednesday night, and then gradually diminish through Thursday night.
“The warning may be expanded to include west facing shores of the Big Island later tonight or Wednesday as the swell makes its way down the island chain,” weather officials said.
Surf along north shores will build to 25 to 35 feet by Wednesday evening, and 15 to 25 feet along west shores.
The islands will see milder weather conditions today with calmer winds and surf and comfortable temperatures.
However, a another large, northwest swell is on the way tonight, forecasters said.
The National Weather Service said the large, long-period swell is expected to build and peak by Wednesday night, bringing surf heights to warning levels. This will be followed by another large, northwest swell expected to build Friday and peak Saturday.
For today, surf along north shores will be 6 to 10 feet before rising to 10 to 20 feet by Wednesday morning and to 20 to 25 feet by Wednesday afternoon.
Surf along west shores will be 3 to 6 feet today, then rise to 6 to 10 feet Wednesday morning and to 10 to 18 feet Wednesday afternoon. Surf along east shores will be 3 to 5 feet today, then lowering into the 2 to 4 foot range Wednesday. Surf along south shores will be 1 to 2 feet through Wednesday.
Some areas will see localized, higher surf on Wednesday due to the large, northwest swell, officials said.
Forecasters, meanwhile, say winds will weaken for the rest of the work week as a front approaches from the northwest.
Today’s forecast includes partly cloudy skies, isolated afternoon showers and highs from 78 to 83 degrees Fahrenheit. East winds of 10 to 15 miles per hour are expected to lower to sea breezes by the afternoon. Tonight’s lows are in the chilly range, from 58 to 67 degrees.
Not much rain is expected for the isles through Friday, other than a few clouds and showers over interior and mauka areas during afternoons. Trades are expected to return briefly over the weekend.