Moderate trades will persist through today, leading to some showers along windward and mauka areas. An upper-level trough moving overhead will produce high clouds and may trigger a few heavy showers and thunderstorms around Kauai and Big Island. Trades will weaken and veer out of the east-southeast across the western half of the island chain tonight and Sunday as low pressure deepens several hundred miles northwest of Kauai. Another passing upper-level trough will bring renewed chances for isolated heavy showers Sunday afternoon and Monday. Light winds favor chances for mainly afternoon showers Tuesday and Wednesday, followed by rebuilding trade winds Thursday and Friday.
Issued at 847 AM HST Sat Apr 18 2026
A jet streak at the base of an upper level trough to the west will continue to supply mid and upper level clouds over the state with embedded showers through much of the morning and possibly into the afternoon. In addition, a line of eastward-moving thunderstorms can be seen about 200 miles northwest of Kauai, but most model guidance has this line weakening and passing just north of the area today.
Otherwise, a mix of moderate to locally breezy easterly trade winds with some sea and land breezes will be in place through the weekend as the surface trough to the west lingers and VFR conditions are expected to generally prevail across most airports. Brief showers will move into windward and mountain areas on the trades, and afternoon showers and thunderstorms will remain possible over interior Big Island. Clouds and showers may also develop over the interior portions of the smaller islands during the day as sea breezes develop. Any afternoon showers could become briefly intense due to the upper level trough providing some instability. These showers would then decrease after sunset as local land breezes occur.
AIRMET Tango is in place between 100 and FL350 due to the potential for some moderate mid to upper level turbulence. This AIRMET will likely be needed through the morning. Light icing will also be possible between 140 and FL250 within the deep layered clouds.
Issued at 326 AM HST Sat Apr 18 2026
A high pressure system far north of the state will slowly drift eastward this weekend. Easterly trade winds continue today with Small Craft Advisory conditions in effect for the windier waters and channels near the Big Island and Maui. A series of low pressure systems developing northwest of the islands will weaken the ridge over the state, causing weak southeasterly winds to develop over the western Hawaii region from Sunday into early next week.
A small pulse of medium period swell energy from the northwest should produce a slight bump in north facing surf heights today. A small to moderate, medium period northwest swell will move into the region by Monday night and continue through Wednesday. A moderate, medium period northeast swell will arrive by Monday night, peaking from Tuesday to early Wednesday, and then slowly declining through Thursday.
A series of overlapping small south swells will move into the region into next week. Surf heights along east facing shores remains on the smaller side due to weaker trade winds.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
