India, March 22 -- Hawaii suffered its worst flooding in more than 20 years as heavy rains fell on soil already saturated by downpours from a winter storm a week ago, officials said Friday, while warning that still more rain was expected during the weekend.

Muddy floodwaters smothered vast stretches of Oahu's North Shore, a community world-renowned for its big-wave surfing. Raging waters lifted homes and cars and prompted evacuation orders for 5,500 people north of Honolulu. Authorities cautioned that a 120-year-old dam could fail.

Gov. Josh Green said the cost of the storm could top $1 billion, including damage to airports, schools, roads, people's homes and a Maui hospital in Kula. "This is going to have a very serious consequence for...