Flash floods and heavy rains from a severe cyclone battered Hawaii for a second day on Tuesday, but the islands have largely been spared the landslides and catastrophic floods that officials had been concerned about.
One of the most inundated parts of the state was Honolulu, which saw floods in urban areas that were caused in part by clogged drains, Adam Weintraub, a spokesman for the Hawaii Emergency Management Agency, said on Tuesday.
The waters were “waist deep” in certain areas of the city, said Richard Bann, a Weather Prediction Center meteorologist for the National Weather Service.
Mr. Weintraub said he had not heard any reports of deaths or injuries, but one woman had to be rescued from her home on Oahu after the wall of her home collapsed.
Parts of Maui were also flooded after “a north-to-south-oriented rain band” hit the island, the Weather Service in Honolulu said on Tuesday afternoon.
The cyclone slamming Hawaii is a type of storm called a kona low, which typically stalls, drops large amounts of rain in one location and comes from a southerly direction, bringing moisture to areas that do not usually get much rainfall, the Weather Service said.
But given the vast expanse of the Pacific Ocean, it is rare for a kona low to stall directly over the Hawaiian islands, meteorologists said.
“This is an extreme weather event,” Mr. Weintraub said on Monday.
A flash flood warning that was in effect for Oahu, the most-populous island, was lifted on Tuesday morning, the Weather Service said. The agency issued flash flood watches from Tuesday afternoon until Wednesday morning for Niihau and Kauai, Hawaii’s westernmost islands.
A “watch,” which means that there is a “significant” risk of floods at an uncertain place or time, is less severe than a “warning,” which indicates that floods are imminent or likely.
Maui had the state’s highest recorded rainfall — 20 inches — on Monday and Tuesday, the Weather Service said. During that same period, parts of Hawaii Island, the state’s largest island, saw more than 14 inches of rain, Oahu nearly 12 inches and Kauai around 4 inches.
Monday was the wettest December day in Honolulu since the Weather Service began tracking rainfall in 1940, Mr. Bann said.
The agency had warned that “numerous” landslides were expected in areas with steep terrain, but Mr. Weintraub said on Tuesday that there had not yet been any major landslides. There was a report, however, of a “three-to-four-foot boulder” blocking a highway, he said.
“Now that rain has started to soak in for a couple days, we are concerned about land moving,” he said, adding that the state authorities were still advising people to stay off the roads.
At least four shelters were open overnight in Oahu, officials said.
Hawaiian Electric, an electricity company on the islands, said on Twitter on Tuesday afternoon that power would not be restored in downtown Honolulu until Wednesday morning.
Gov. David Ige of Hawaii signed an emergency declaration on Monday afternoon, which freed state funds to be used for losses caused by flooding and other effects of the cyclone. The mayors of Hawaii and Honolulu counties also declared states of emergency.
On Tuesday, portions of several major roadways were closed as emergency crews cleared fallen rocks and downed trees and power lines, according to the Hawaii Department of Transportation.
Hawaii’s natural geography, including lava and water, left the state at risk of severe floods because “everything runs off” easily from the slick volcanic rocks covering the islands, David Roth, a meteorologist with the Weather Service, said on Monday.
“For areas that are volcanic, you’re dealing with steep slopes, especially in places where people are living near the base of them — so yeah, that’s a problem,” he said.
The storm system also brought snow to the Big Island summits, which rise to well over 11,000 feet. But meteorologists said that was not an uncommon elevation for snow to fall, even on a tropical island — and that the rain was a much more important concern.
“I worry that one of our social media posts made everyone focus on the blizzard rather than the rain, which is exactly the same system,” Mr. Roth said.
It is unusual for a storm system like the one this week to linger over Hawaii, but it is not possible to immediately draw a connection between one heavy downpour and climate change. Climate scientists may try to do that, by undertaking what is known as an attribution study, in the coming weeks or months.
But the United States and other parts of the world have already seen an increase in the frequency of extreme rainstorms as the world warms. And the frequency is likely to increase as warming continues. One basic reason is that warmer air holds more moisture.
Jesus Jiménez, Derrick Bryson Taylor and Johnny Diaz contributed reporting.