National Weather Service forecasters say an unseasonably deep low-pressure system will approach the Hawaiian islands from the north over the next 24 hours, bringing humidity and rain this weekend.

The system will bring light southeasterly to southerly winds, resulting in deep and unstable tropical moisture from Friday through Monday as well as numerous showers and isolated thunderstorms.

Today’s forecast is still sunny, with partly cloudy skies in the afternoon and highs from 80 to 85 degrees Fahrenheit. Tradewinds have slowed to 10 mph in the morning and will increase up to 15 mph by this afternoon. Tonight’s lows are from 65 to 70 degrees, with variable winds up to just 10 mph.

On the surf front, a new swell building Saturday will produce moderate surf along north and west shores over the weekend, but well below the advisory threshold.

Surf will remain fairly low, overall, at 4 to 6 feet today along south shores before lowering to 2 to 4 feet Friday. Surf along north shores will be 2 to 4 feet today before subsiding to 1 to 3 feet Friday.

Surf along west shores will be 1 to 3 feet today, lowering to 2 feet or less Friday. Surf along east shores will be to 2 to 4 feet through Friday.

Showers are expected to spread across the isles from west to east from Friday into the weekend. Periods of unsettled weather may last into the first half of next week due to this persistent low lingering northwest of the state.