513  
FXHW60 PHFO 140143  
AFDHFO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HONOLULU HI  
343 PM HST SAT SEP 13 2025  
   
SYNOPSIS
 
 
HIGH PRESSURE CENTERED NORTHEAST OF HAWAII WILL DRIVE MODERATE TO  
FRESH TRADE WINDS WITH DRY AND STABLE WEATHER INTO NEXT WEEK.  
AN UPPER TROUGH WILL DRIFT THROUGH THE ISLANDS FROM TUESDAY TO  
THURSDAY POSSIBLY INCREASING SHOWERS.  
 

 
   
DISCUSSION
 
 
HIGH PRESSURE CENTERED NORTHEAST OF HAWAII WILL DRIVE MODERATE TO  
FRESH TRADE WINDS WITH DRY AND STABLE WEATHER INTO NEXT WEEK.  
VISIBLE SATELLITE SHOWS CLOUD BUILD UPS OVER LOWER SLOPES ON THE  
BIG ISLAND, AND A FEW CIRRUS CLOUDS PASSING OVER THE STATE. OTHERWISE  
CONDITIONS ARE MOSTLY SUNNY TO PARTLY CLOUDY WITH VIRTUALLY NO  
PRECIPITATION OBSERVED ON RADAR. THE OVERALL PATTERN WILL CHANGE  
LITTLE THROUGH MONDAY, WITH THE BEST CHANCE FOR RAINFALL AND CLOUD  
COVER OVER THE WINDWARD SLOPES, BUT ACCUMULATIONS WILL BE LIGHT.  
 
A TROPICAL WAVE WILL PASS SOUTH OF THE STATE TUESDAY THROUGH  
THURSDAY. UPPER LEVEL TROUGHING WILL SET UP OVER THE STATE AROUND  
THE SAME TIME MAY ACT TO ENHANCE SHOWERS MOVING IN ON BOTH THE  
TRADE WIND FLOW AND THE FAR NORTHERN PERIPHERY OF THE WAVE. CLOUDS  
AND SHOWERS WILL LIKELY INCREASE DURING THIS TIME FRAME FOCUSING  
OVER WINDWARD AND MAUKA AREAS. THE UPPER TROUGH MAY BECOME AN  
UPPER LOW AND DEEPEN NEXT WEEKEND POSSIBLY FURTHER ENHANCING  
RAINFALL.  
 

 
   
AVIATION
 
 
MODERATE TO LOCALLY BREEZY TRADE WINDS WILL PERSIST FOR THE NEXT  
FEW DAYS AS HIGH PRESSURE REMAINS SITUATED NORTHEAST OF THE STATE.  
BRIEF PASSING SHOWERS WILL FAVOR WINDWARD AND MOUNTAIN AREAS IN  
THE OVERNIGHT TO EARLY MORNING HOURS. VFR CONDITIONS WILL PREVAIL  
OUTSIDE OF SHOWERS.  
 
NO AIRMETS ARE IN EFFECT.  
 

 
   
MARINE
 
 
LITTLE CHANGE IN THE FORECAST WITH THE AFTERNOON PACKAGE.  
 
HIGH PRESSURE WILL REMAIN NEARLY STATIONARY NORTH OF THE ISLANDS  
INTO MONDAY. MEANWHILE A LOW PRESSURE SYSTEM TO THE SOUTHEAST OF  
THE ISLANDS WILL MOVE TO THE WEST. THE RESULTANT PRESSURE GRADIENT  
OVER THE ISLANDS WILL MAINTAIN THE MODERATE TO LOCALLY STRONG  
TRADES THROUGH SUNDAY. HEADING INTO SUNDAY NIGHT AND MONDAY, WINDS  
WILL WEAKEN AS THE HIGH TO THE NORTH IS ERODED BY A COLD FRONT  
MOVING WEST TO EAST. A SMALL CRAFT ADVISORY (SCA) REMAINS IN  
EFFECT FOR THE WINDIER WATERS NEAR MAUI COUNTY AND THE BIG ISLAND.  
THIS SCA IS IN PLACE THROUGH SUNDAY AFTERNOON, WITH WINDS EXPECTED  
TO FALL BELOW SCA LEVELS SUNDAY NIGHT. HIGH PRESSURE BUILDING  
NORTH OF THE ISLANDS BEHIND THE ABOVE MENTIONED COLD FRONT, WILL  
ALLOW TRADE WINDS TO INCREASE AGAIN TUESDAY NIGHT INTO WEDNESDAY,  
WHEN ANOTHER SCA MAY BE NEEDED.  
 
NO ADVISORY LEVEL SWELL ARE EXPECTED THIS WEEK. THE CURRENT  
SMALL, MEDIUM PERIOD SOUTH SWELL WILL CONTINUE TO FALL OVER THE  
REMAINING DAYLIGHT HOURS TODAY, WITH A SMALL LONGER PERIOD  
REINFORCEMENT SWELL EXPECTED TO ARRIVE TONIGHT. THAT WILL HOLD THE  
SURF ALONG SOUTH FACING SHORES AROUND WAIST HIGH THROUGH SUNDAY.  
THE CURRENT NORTH SWELL WILL CONTINUE TO DECLINE THROUGH SUNDAY.  
ANOTHER SMALL, MEDIUM PERIOD NORTH SWELL IS EXPECTED TO ARRIVE  
THURSDAY, CAUSING A SMALL BUMP IN SURF LATE IN THE WEEK. TYPICAL  
SHORT PERIOD WIND WAVE CHOP WILL OCCUR ALONG EAST-FACING SHORES  
WITH THE MODERATE TO LOCALLY STRONG TRADES THIS WEEKEND.  
 

 
   
FIRE WEATHER
 
 
HUMIDITY LEVELS WILL REMAIN DRY INTO NEXT WEEK WITH INCREASING  
HUMIDITY AND SHOWER TRENDS FROM TUESDAY INTO WEDNESDAY AS A WEAK  
LOW LEVEL TROUGH DRIFTS FROM EAST TO WEST ACROSS THE ISLAND CHAIN.  
WIND SPEEDS WILL LIKELY REMAIN BELOW CRITICAL FIRE WEATHER  
THRESHOLDS FOR THE NEXT SEVEN DAYS. TEMPERATURE INVERSION HEIGHTS  
NEAR THE BIG ISLAND AND MAUI WILL RANGE FROM 5,500 TO 6,500 FEET  
THROUGH THE WEEKEND.  
 

 
   
HFO WATCHES/WARNINGS/ADVISORIES
 
 
SMALL CRAFT ADVISORY UNTIL 6 PM HST SUNDAY FOR MAALAEA BAY-  
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG  
ISLAND SOUTHEAST WATERS.  
 

 
 

 
 
DISCUSSION...FOSTER  
AVIATION...FARRIS  
MARINE...M BALLARD  
FIRE WEATHER...FOSTER  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HI Page Main Text Page