Hawaii is preparing for a powerful storm this week that is expected to cause intense winds, thunderstorms and possibly significant flooding across multiple islands.

Josh Green, the governor, said on Monday he had issued an emergency proclamation in response to the weather expected to hit his state in the coming days, in order to bring additional resources into affected areas.

“It’s going to be kind of a rough and tumble week with the weather,” Green said in a video posted on social media. “Be very safe. Be particularly safe on the roads.”

The National Weather Service (NWS) has advised that a “large and powerful kona storm” will deliver heavy rainfall, causing flooding on smaller islands and in urban areas, as well as potentially severe thunderstorms and gusty winds. It will first hit Kauai, Niihau and Oahu on Tuesday, before expanding to the other islands in the coming days.

Later in the week, the islands could see more damaging conditions, the governor’s office said in a statement.

The state has closed several parks and trails in response to the forecast, and urged people to avoid both forested and coastal areas, citing the dangers of storm surge, high surf, rising streams and falling trees.

“Our priority is keeping the people of Hawaii safe,” Green said.

A flood watch is in effect until Saturday, and the NWS has said residents should be prepared by identifying evacuation routes and shelters, and planning for pets and vulnerable family members.

A meteorologist with the NWS told the San Francisco Chronicle the islands could see more than 20in of rain in some areas. “But that’s just a ballpark estimate,” Laura Farris said.

On Hawaii’s Big Island, Kilauea began to erupt on Tuesday, shooting lava fountains as high as 1,000ft (300 metres) and prompting warnings of falling glassy volcanic fragments and ash.

The fountaining that started on Tuesday morning marked the eruption’s 43rd episode since it began in December 2024. Like other times, the molten rock was confined within Kilauea’s summit crater inside Hawaii Volcanoes national park and hasn’t threatened homes or buildings.

But the lava fountains were creating trouble for neighboring communities and a highway where the volcanic fragments and ash, known as tephra, was falling. The tephra prompted temporary closures at the national park around the summit and a partial closure of Highway 11, an important route around the island, on either side of the park.

Hawaii county officials also opened a shelter at a district gymnasium for residents and tourists impacted by the road closure or falling tephra. The National Weather Service issued an ashfall warning.

Volcanic tephra can irritate eyes, skin and the respiratory system, according to county officials. Tephra also can clog and cause other problems with water catchment collection systems, which are common in some parts of the Big Island, officials said.

Associated Press contributed reporting