textproduct: Honolulu

UPDATE

Update to include Fire Weather section.

SYNOPSIS

Partly to mostly cloudy conditions with intermittent rain and breezy trades the next couple of days. The probability of isolated thunderstorms will exist in the vicinity of Kauai and Oahu and their surrounding coastal waters today. An approaching cold front will weaken trades tonight through Wednesday but it will become breezy again by late week as high pressure to the north of the region passes into the eastern Pacific. The weather pattern may become more overcast and wet early next week in response to an early November development of an upper trough in the proximity of the state.

PREV DISCUSSION

/ISSUED 400 AM HST Tue Oct 28 2025/

Satellite depicting a wide array of various level clouds as a weakness in upper ridging across the Hawaiian Isles holds these unsettled conditions. Most of the overnight precipitation has been focused over the western third of the CWA where Kauai has received most of the action. A quick one to two inches and responding streams across the Garden Isle had a short fuse Flood Advisory in effect. An approaching cold front nearing our far northwestern offshore waters is beginning to stall. Backing high pressure behind it will maintain a tight enough downstream gradient to support gentle to moderate trades the remainder of the week. The passage of the subtropical jet across the state to the east through early Wednesday will allow the transport of more moisture rich air to advect over in the form of a broken cloud shield. A more organized trough is developing in this height weakness channel between the two ridges on either side of the island chain. The trough is forecast to deepen and allow cold -8 C to -11 C 500 mb air to sink down over the region through Wednesday morning or afternoon. This cooler air atop warm, humid lower level air moving up on the eastern flank of the trough will destabilize the atmosphere and introduce a mentionable threat for isolated thunderstorms. The greatest probability for heavy rainfall and lightning will be across the northern coastal waters...with a slight chance that either Kauai or Oahu gets clips by a passing maritime storm. The trough may deepen enough to pinch off a cut off upper level low south of the islands by Thursday. If this occurs, the threat for more organized rain and/or thunderstorms will shift far south of the state. Most across the majority of the island chain will experience a partially to mainly overcast Tuesday through Thursday with most of the more frequent trade showers focusing along windward upslope mauka and within higher terrain.

Drier air begins to work into the area along eastern steering winds late in the week. Upper ridging attempts to expand in from the west but troughing will hold on over the area going into the weekend. It will be relatively drier Friday and Saturday, but various clouds at different levels will still shroud the state. An early November cold front may have enough steam to reach the northern coastal waters over the weekend and back winds more northerly by Sunday. Model guidance is in disagreement with the strength of the associated upper trough as it travels east across the north central Pacific. Keeping rain chances higher over the northern latitudes early next week to account for the moderate possibility of a lower level trough/front hanging up north of the state therefore providing the necessary convergence for more areawide rain.

FIRE WEATHER

Lower level humidity is forecast to be high enough through the week, along with more frequent showers, to keep fire weather conditions below critical thresholds. Trades winds will be relatively weaker, gentle to moderate in magnitude. Temperature inversion heights will be a little lower today, from 4,500 to 6,500 ft.

HFO WATCHES/WARNINGS/ADVISORIES

None.