A cold frontal system is approaching the islands from the northwest, prompting the National Weather Service to issue a flash flood watch for Kauai County, effective from 6 p.m. today through late Wednesday night.
Forecasters say a stalling cold front will approach Niihau and Kauai from the west tonight, bringing the potential for slow-moving shower bands and periods of heavy showers that could lead to flash flooding.
While it remains uncertain how far east the front will move, the risk of flash flooding will be high if it stalls over Kauai County.
Normally dry leeward areas may receive heavy rainfall leading to flash flooding, forecasters said, while windward areas could be affected as well, and Kuhio Highway will be at risk of closing near the Hanalei bridge.
Enhanced showers are also forecast for the east to southeast slopes of Hawaii island for the next few days.
For Kauai County, showers are forecast to last through Thanksgiving on Thursday morning for Kauai and Niihau, before returning tradewinds push the showers away from the isles by the afternoon. For all isles, trades will bring shower activity back toward windward and mountain areas by Thursday night.
The NWS has also issued a warning for possible coastal flooding for all shores around the state this week due to unusually high water levels.
Peak high tides are expected during early morning hours from today through Friday. More specific information about forecast tides and water levels are available at tidesandcurrents.noaa.gov.
Today will be mostly sunny for most isles, with isolated showers and highs from 83 to 88 degrees Fahrenheit and southeast winds of 10 to 20 miles per hour. Lows tonight are from 70 to 75 degrees.
Surf along north facing shores will be 3 to 6 feet today, rising to 8 to 12 feet Wednesday. Surf along west shores will be 2 to 4 feet today, rising to 5 to 8 feet Wednesday.
Surf along east shores will be 5 to 7 feet today, lowering to 4 to 6 feet Wednesday. Surf along south shores will remain at 1 to 3 feet through Wednesday.
A new northwest swell is expected to arrive tonight and peak on Wednesday, and surf may approach advisory levels along exposed north and west shores of some of the smaller isles on Wednesday, then gradually subside Thursday through Friday.
A small craft advisory for windward Maui County and Big Island waters, as well as leeward and southeast Big Island waters, remains in effect until 6 p.m. today.
More records, meanwhile, are being set this month. A record high of 87 degrees in Honolulu on Monday matched the previous one set in 1983. A record high of 91 degrees at Kahului broke the previous one of 90 set in 1956.