The strong tradewinds of the last week are weakening and may be replaced by more humid weather and rain starting Tuesday night or Wednesday morning.

The weather service says a cold front is expected to move over the state from the northwest starting Tuesday night.

Forecasters expect muggy conditions and an increased chance of rain for Kauai starting Tuesday and moving over Oahu Wednesday.

A high surf advisory was extended to 6 p.m. Tuesday as the strong east winds slowly diminish. Surf was expected to be 6 to 9 feet tonight, lowering to 5 to 8 feet Tuesday.

Forecasters say another weather system moving up from the east will merge with the cold front from the west, creating unstable weather later in the week.

The conditions created by the collision of the two weather systems could bring heavy rains this weekend, including possible thunderstorms and flooding, starting Thursday.

Meanwhile, Hilo tied another high temperature record Sunday. The high of 85 at the Hilo Airport tied a record for the date last set in 2006. It’s the fifth high temperature this month in Hilo.

The forecast for Honolulu and south shores of Oahu calls for mostly sunny to partly sunny skies Tuesday into Wednesday. Winds will turn towards the southeast, bringing Kona weather conditions.

There’s a 50 percent chance of rain Wednesday night, when skies are expected to become mostly cloudy. Scattered showers and a slight chance of thunderstorms is forecast for Thursday.

Friday may bring cloudy skies with frequent showers and the possibility of locally heavy rain.

The rainy weather is expected to continue through Monday.