Moderate to locally breezy trades will prevail through today, decreasing slightly by tomorrow, before easing to a more light and variable pattern by this weekend. Shower activity will be kept to a minimum as a cooler and drier airmass filters over the Hawaiian Islands. A cold, upper-level trough makes an appearance late in the week and may slightly enhance trade wind showers, but any meaningful rainfall still remains unlikely.
Issued at 316 AM HST Tue Mar 31 2026
An upper-level trough remains just northeast of the Hawaiian Islands, continuing to slowly shift northeast, while a broad 1032 mb surface high building in its wake from the northwest. These features will be the catalyst to driving moderate to locally breezy trades across statewide through much of today. Guidance suggests today will be the windiest day of the week, though most locations will remain just below Wind Advisory thresholds. However, it cannot be ruled out that some of the more usual wind- prone locations could occasionally edge near the criteria.
Shower activity will also focus low clouds and showers across windward and mauka areas, but rainfall will be sparse. Latest model guidance continues to show precipitable water values two to three standard deviations below average. This is largely due to a drier airmass filtering in over the entire state. Some guidance preserve the slight uptick in thunderstorm potential of up to 15 percent over the southern slopes of the Big Island. However, with moisture levels running exceptionally low, any storms that do form would likely be "dry" thunderstorms, producing lightning with little to no rainfall. Given that the atmosphere may still be too dry, confidence of storm development, too, remains low.
Looking ahead, trades will begin to ease by tomorrow as the aforementioned high pressure will begin to weaken, becoming light and variable by this weekend and persisting that way through the remainder of the forecast period. Right around the same time, a weak upper- level trough is anticipated to pass within the vicinity of the islands. Moisture will remain limited, though, and any meaningful increase in rainfall still appears unlikely at this time. This system will be monitored and refined throughout the next several days as the pattern evolves.
Issued at 316 AM HST Tue Mar 31 2026
Moderate to locally breezy trade winds will continue into tonight. Winds will taper off tomorrow morning. Isolated showers are possible tonight along windward and mauka areas which may lower ceilings and visibilities to MVFR at times. Otherwise, VFR conditions will prevail.
AIRMET Tango is in effect for mod turb blw 080 downwind of terrain.
Issued at 905 AM HST Tue Mar 31 2026
The pressure gradient between a high located about 800 nm north of Oahu and a trough just east of the far offshore waters will slightly weaken through mid week. The result will be trades falling back to more moderate magnitudes Wednesday morning and remaining at these speeds through the remainder of the week. The Small Craft Advisory for moderate to locally fresh trades remains in effect until 6 PM HST today. A trough forming between the exiting high to the northeast and the next high moving in from the west central Pacific will maintain gentle to moderate trades this weekend.
North and east-facing shore surf will remain under advisory heights as near 9 foot, short period NNE (020-030 degree) veering swell holds through the day and then slowly falls through the week. There is still enough of a northerly component to the swell to continue to message the potential for minor surges within north- facing harbors today. Shores better exposed to this NNE swell will experience decent wind wave chop generated by solid moderate trades.
South shore surf will remain small this week with only background swell providing minor pulses the next several days. Any source, such as Southern Hemispheric gale lows, will be too far south and moving at too quick of an easterly pace to push any significant swell up into our local southern waters going through the first week of April.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.
