Honolulu starts Sunday under cloudy skies, breezy winds and temperatures near 77 degrees, but the bigger story is building offshore. Frequent showers are expected this afternoon, with heavier rain, thunderstorms and dangerous surf becoming more likely as Hurricane Lowell pulls tropical moisture toward the islands.
Oahu could reach about 86 degrees Sunday, with east-northeast winds running 10 to 16 mph and gusts up to 23 mph. Rain chances rise sharply around midday, and showers may become persistent by evening instead of the usual quick trade-wind sprinkle.
Flood Watch Covers Oahu Through Tuesday
A flood watch is in effect from noon Sunday through Tuesday afternoon for Oahu and the other main Hawaiian Islands. The National Weather Service in Honolulu says heavy rain could cause rapid runoff, flooding on low-lying roads and overflowing streams, with the threat spreading beyond windward areas as winds turn more southerly.
Sunday night brings a 90% chance of showers and thunderstorms, with some storms capable of producing heavy rain. Rain totals could reach three-quarters of an inch overnight, while Monday is expected to be the roughest day for Oahu, with frequent thunderstorms, a 100% chance of rain and possible rainfall totals between 1 and 2 inches.
Surf Builds Before The Week Turns Wetter
A high surf advisory remains in effect through early Tuesday for south- and east-facing shores, including Honolulu-area beaches. Surf could reach roughly 10 feet along affected shores and rise toward 14 feet Sunday night, while south- and west-facing beaches may see warning-level conditions on Monday as Lowell approaches west of Kauai.
Honolulu is not under the tropical storm warning issued for Kauai and Niihau, but Oahu can still see serious rain, surf and isolated storm hazards well away from the hurricane's center. Swimmers, surfers and boaters should follow ocean safety guidance, and drivers should never attempt to cross a flooded roadway.
Rain Eases Later In The Week
Showers remain frequent Tuesday, with a high near 88 and an 80% rain chance, then taper somewhat Wednesday. Conditions should improve Thursday, when morning showers give way to mostly sunny skies, followed by mostly sunny weather Friday and Saturday with only isolated showers.
The update marks a meaningful escalation from Hoodline's earlier forecast, which focused mainly on gusty trades and choppy surf. For Honolulu residents, the practical takeaway is simple: secure loose outdoor items, keep flood-prone routes in mind and plan for a very wet Monday.
