textproduct: Honolulu

SYNOPSIS

Moderate to locally breezy trades will continue this week as high pressure remains anchored well north of the state. A relatively dry and stable air mass will keep windward showers sparse and leeward areas mostly dry. Trades may ease briefly late this week before strengthening again next weekend as high pressure rebuilds to the north. Tropical systems far east of the state will be monitored, but pose no immediate impacts to the islands.

SHORT TERM UPDATE

A quiet and fairly dry evening as an upper ridge centered out west toward the Dateline has expanded eastward and engulfed the central Pacific. This ridging has provided the subsidence and greater stability required in maintaining a dry short term (evening into early Monday) forecast. Recent oceanic surface analysis depicts no features over or in the vicinity of the islands. The closest features of any worthy mention are weak lower level lows and associated troughs far south of the state, west of the ITCZ that has nudged west of 140W. High clouds from the subsequent storms produced by these surface features may get caught up within the upper southwesterly flow, travel over the area tonight and result in occasionally milky skies in contrast to a generally mainly clear canopy.

There will be an uptick in showers going through the day and into evening tomorrow and Tuesday as higher moisture moves in from the east. Slightly below seasonable column precipitable water values of around 1.2 to 1.3" will be on the rise back to near normal levels (around 1.4") in response to greater mid layer moisture advection. Higher layer humidity will be the impetus to increased shower frequency and coverage both Monday and Tuesday. Much drier air following this moist air mass Wednesday onward will ensure a drier mid to late week.

PREV DISCUSSION

Issued at 321 PM HST Sun Jul 19 2026 Satellite shows mostly clear skies over most of the state this afternoon, while radar indicates isolated light showers in a few windward areas. Trade winds continue at 10 to 20 mph with gusts just over 30 mph in the usual windy spots.

A broad surface high centered well north of the state remains the dominate synoptic feature on our weather map, supporting moderate to locally breezy trades this week. Trade wind showers will remain limited as a relatively dry air mass persists. Model guidance suggests a slight increase of moisture Tuesday into Wednesday, but it will only lead to a slight increase in showers. Overall, we'll see isolated, light windward and mauka showers, with leeward areas remaining predominately dry.

Forecast confidence late in the week becomes increasingly dependent on the evolution of the tropical disturbances currently located well east of us. While deterministic and ensemble guidance suggests some westward progression, it remains too early to determine whether any of these systems or their associated moisture will influence the Hawaiian Islands. At this time, no changes to the sensible weather forecast are warranted, though these tropical features will continue to be monitored closely over the coming days.

AVIATION

Moderate trades will continue through the forecast period. VFR conditions will prevail except isolated MVFR conditions over windward and mauka areas in clouds and showers.

No AIRMETs are in effect and none are anticipated through the forecast period.

MARINE

The trade winds will ease tonight as high pressure north of the islands weakens, with the trades then holding at moderate speeds Monday through Tuesday. The trades will restrengthen back to fresh and locally strong speeds Wednesday through Friday as high pressure strengthens north of the island chain.

A south swell is expected to build tonight, then peak around the advisory level late Monday into early Wednesday. A High Surf Advisory will likely be required through this period. As this swell slowly fades during the middle of the week, a new long period south swell will arrive on Thursday, keeping surf elevated through next weekend.

Surf along north-facing shores will remain at flat to tiny levels through next weekend.

Surf along east facing shores will lower slightly Monday through Wednesday as the trades ease upstream of the islands. East shore surf should then build back close to seasonal levels late in the week through next weekend. Additionally, swell from Tropical Storm Elida may give a slight boost to east shore surf during the middle of the week.

HFO WATCHES/WARNINGS/ADVISORIES

None.