The return of the tradewinds and a developing weather system could make for a wet Halloween weekend.

National Weather Service forecasters say a weather system forming northeast of the islands will move closer to the state Friday bringing unstable and moist atmospheric conditions and the chance of isolated heavy rain this weekend.

There is also chance of thunderstorms Saturday for Hawaii island and Maui.

Another weather system west of the islands that had blocked the tradewinds has weakened and moved away. 

That means a return to the usual windward and mauka showers that could spread leeward.

"We’re going to be in a tradewind pattern," said Bob Burke, a forecaster with the National Weather Service. "But there’s going to be higher chances of rainfall, particularly in the windward and mauka areas."

Burke said the weather system north of the islands is bringing more moisture to the state and destabilizing the atmosphere.

Trick-or-treaters on Monday can expect some clouds and the possibility of light showers, especially in windward and mauka areas, Burke said. Some of those showers could blow over the mountains to leeward areas.