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FXHW40 KWBC 161231
PMDHCO
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THU JUL 16 2026
MONTHLY FORECAST DISCUSSION VALID AUGUST 2026
SEA SURFACE TEMPERATURE (SST) ANOMALIES IN THE RANGE OF 0 TO +1 DEGREES CELSIUS
(C) WERE OBSERVED AROUND THE HAWAIIAN ISLANDS (KAUAI, OAHU, MAUI AND THE BIG
ISLAND) DURING THE PREVIOUS WEEK WITH WARMER ANOMALIES NEAR THE BIG ISLAND AND
WEAKER ANOMALIES NEAR KAUAI.
FROM JANUARY THROUGH JUNE 2026, RAINFALL TOTAL ACCUMULATIONS WERE:
LIHUE AIRPORT 35.41 INCHES (197 PERCENT OF AVERAGE)
HONOLULU AIRPORT 21.10 INCHES (256 PERCENT OF AVERAGE)
KAHULUI AIRPORT 27.92 INCHES (302 PERCENT OF AVERAGE)
HILO AIRPORT 76.11 INCHES (140 PERCENT OF AVERAGE)
MOST CLIMATE MODELS OF THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND THE
INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME/C3S) PREDICT POSITIVE SST ANOMALIES
AROUND THE HAWAIIAN ISLANDS IN AUGUST 2026. BASED ON MODEL SST AND SURFACE AIR
TEMPERATURE FORECASTS, ABOVE NORMAL TEMPERATURES ARE FAVORED FOR KAUAI (LIHUE),
OAHU (HONOLULU), MAUI (KAHULUI), AND THE BIG ISLAND (HILO).
FOR THE AUGUST 2026 PRECIPITATION OUTLOOK, THE PROBABILITY OF ABOVE NORMAL
PRECIPITATION IS ELEVATED FOR ALL ISLANDS OF HAWAII, WITH GREATER PROBABILITIES
FOR SOUTHEASTERN ISLANDS AND WEAKER PROBABILITIES FOR NORTHWESTERN ISLANDS. THE
OUTLOOK IS CONSISTENT WITH MOST MODELS OF THE NMME AND IMME, AS WELL AS
STATISTICAL FORECASTS FROM THE CONSTRUCTED ANALOG (CA).
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
HILO A70 76.6 0.4 A55 7.6 8.4 10.3
KAHULUI A70 79.8 0.4 A50 0.3 0.5 0.6
HONOLULU A60 82.1 0.4 A45 0.1 0.2 0.4
LIHUE A50 79.7 0.4 A40 1.4 1.8 2.5
SEASONAL FORECAST DISCUSSION VALID ASO 2026 - ASO 2027
REFER TO THE PROGNOSTIC DISCUSSION OF THE LONG-LEAD SEASONAL OUTLOOKS FOR THE
CONTIGUOUS U.S. (CONUS) AND ALASKA FOR FURTHER DESCRIPTION OF THE EL NINO
SOUTHERN OSCILLATION (ENSO) OUTLOOK AND OTHER CLIMATE CONDITIONS RELEVANT TO
THE SEASONAL OUTLOOK.
CURRENT ATMOSPHERE AND OCEAN CONDITIONS REFLECT EL NINO. RELATIVE SST
ANOMALIES, THAT REMOVE THE GLOBAL TROPICAL AVERAGE ANOMALY, ARE POSITIVE ACROSS
THE CENTRAL AND EASTERN EQUATORIAL PACIFIC OCEAN AND NEGATIVE IN THE WESTERN
EQUATORIAL PACIFIC OCEAN. THE MOST RECENT 3-MONTH RELATIVE OCEAN NINO INDEX
(RONI) FOR APRIL THROUGH JUNE IS +0.5 DEGREES C, REPRESENTING THE FIRST SEASON
OF THIS STRENGTHENING EL NINO. WEEKLY AVERAGE RELATIVE SST ANOMALIES FOR THE
NINO 3.4 REGION ARE CURRENTLY ABOUT +1.3 DEGREES C, EXCEEDING THE THRESHOLD FOR
A MODERATE STRENGTH EL NINO. RELATIVE SST ANOMALIES SUBTRACT THE AVERAGE GLOBAL
TROPICAL SST ANOMALY BETWEEN 20 DEGREES S AND 20 DEGREES N LATITUDE. POSITIVE
SST ANOMALIES ARE OBSERVED ACROSS MOST OF THE TROPICAL PACIFIC OCEAN TO THE
NORTH OF 10 DEGREES N LATITUDE, INCLUDING IN THE VICINITY OF THE HAWAIIAN
ISLANDS.
ABOVE-AVERAGE SUBSURFACE OCEAN TEMPERATURES HAVE PERSISTED ACROSS THE CENTRAL
AND EASTERN EQUATORIAL PACIFIC OCEAN FROM THE SURFACE TO DEPTHS OF 200 METERS
FROM ABOUT THE INTERNATIONAL DATE LINE TO SOUTH AMERICA. BELOW-AVERAGE OUTGOING
LONGWAVE RADIATION (OLR), ASSOCIATED WITH ENHANCED CONVECTION AND
PRECIPITATION, IS OBSERVED NEAR AND WEST OF THE DATE LINE AND OVER THE
EAST-CENTRAL EQUATORIAL PACIFIC OCEAN, WHILE ABOVE-AVERAGE OLR, ASSOCIATED WITH
SUPPRESSED CONVECTION AND PRECIPITATION, IS OBSERVED OVER MUCH OF THE MARITIME
CONTINENT. LOW-LEVEL (850-HPA) WIND ANOMALIES ARE WESTERLY FROM THE WESTERN TO
THE EAST-CENTRAL EQUATORIAL PACIFIC OCEAN, WHILE UPPER-LEVEL (200-HPA) WIND
ANOMALIES ARE EASTERLY FROM THE WESTERN TO EAST-CENTRAL EQUATORIAL PACIFIC AND
WESTERLY OVER THE EASTERN EQUATORIAL PACIFIC.
THE MADDEN JULIAN OSCILLATION (MJO) IS CURRENTLY CONSTRUCTIVELY INTERFERING
WITH THE EL NINO BACKGROUND STATE. THE ENHANCED CONVECTION HAS BEEN STATIONARY
OVER THE WESTERN PACIFIC DURING THE PAST WEEK. DYNAMICAL MODELS PREDICT THE
RESUMPTION OF AN EASTWARD PROPAGATION OF THE MJO INTO THE WESTERN HEMISPHERE
DURING THE NEXT WEEK, FOLLOWED BY GRADUAL DISORGANIZATION LATER IN JULY. A
PERIOD OF DESTRUCTIVE INTERFERENCE WITH THE EL NINO BACKGROUND STATE MAY OCCUR
AS AUGUST BEGINS. HOWEVER, EL NINO IS EXPECTED TO DOMINATE THE TROPICAL CLIMATE
STATE THROUGHOUT THE MONTH OF AUGUST.
DYNAMICAL AND STATISTICAL MODELS PREDICT THE STRENGTHENING OF THE EL NINO
THROUGH THE END OF THE YEAR, AND PERSISTENCE OF EL NINO CONDITIONS INTO NEXT
SPRING. DYNAMICAL MODEL FORECASTS, INCLUDING THE NORTH AMERICAN MULTIMODEL
ENSEMBLE (NMME) MEAN, PREDICT PEAK RONI VALUES EXCEEDING +2.5 DEGREES C IN LATE
BOREAL AUTUMN AND EARLY WINTER. STATISTICAL TOOLS, SUCH AS THE CPC CONSTRUCTED
ANALOG (CA) AND CPC CANONICAL CORRELATION ANALYSIS (CCA) PREDICT A LOWER
AMPLITUDE EL NINO EVENT, BUT STILL EXCEED THE +1.5 DEGREES C THRESHOLD FOR A
STRONG EVENT. A STRONG EL NINO EVENT IS CONSIDERED ALMOST CERTAIN WITH
PROBABILITIES EXCEEDING 95 PERCENT THROUGH THE AUTUMN INTO EARLY WINTER.
HISTORICALLY, EL NINO CONDITIONS FAVOR ABOVE NORMAL PRECIPITATION FOR HAWAII IN
THE BOREAL SUMMER AND EARLY AUTUMN AND BELOW NORMAL PRECIPITATION IN LATE
AUTUMN AND WINTER SEASONS. THE HAWAII SEASONAL OUTLOOK FOR TEMPERATURE AND
PRECIPITATION IS BASED PRIMARILY ON DYNAMICAL MODEL FORECASTS FROM THE NMME AND
STATISTICAL FORECASTS, INCLUDING THE CA. THE IMPACTS OF THE CURRENT AND
PREDICTED EL NINO ON THE TEMPERATURE AND PRECIPITATION FOR HAWAII ARE A PRIMARY
DRIVER OF THE HAWAII SEASONAL OUTLOOK IN MOST SEASONS.
ABOVE NORMAL TEMPERATURES ARE LIKELY IN THE OUTLOOK FOR LIHUE, HONOLULU,
KAHULUI AND HILO BEGINNING IN AUGUST-SEPTEMBER-OCTOBER (ASO) WITH THE
PROBABILITY OF ABOVE NORMAL TEMPERATURES EXCEEDING 70 PERCENT ACROSS THE ISLAND
CHAIN. ABOVE NORMAL TEMPERATURES CONTINUE TO BE FAVORED THROUGH
DECEMBER-JANUARY-FEBRUARY (DJF) 2026-27 FOR HILO, THROUGH
NOVEMBER-DECEMBER-JANUARY (NDJ) FOR KAHULUI AND HONOLULU, AND THROUGH
OCTOBER-NOVEMBER-DECEMBER (OND) FOR LIHUE, SUPPORTED BY DYNAMICAL MODEL
FORECASTS FROM THE NMME AND C3S, AND THE CA STATISTICAL MODEL. THE OUTLOOK IS
ALSO CONSISTENT WITH EL NINO IMPACTS WITH THE ADDITION OF DECADAL TIMESCALE
TEMPERATURE TRENDS FOR THE REGION. EL NINO IMPACTS TEND TO LEAD TO COOLER THAN
AVERAGE TEMPERATURES FOR NORTHWESTERN ISLANDS OF HAWAII AS THE WINTER
PROGRESSES. HOWEVER, DUE TO INCREASING UNCERTAINTY IN THE IMPACTS OF ENSO AND
WEAKENING SIGNALS IN FORECAST GUIDANCE AT LONGER LEADS, EQUAL CHANCES (EC) FOR
ABOVE, NEAR OR BELOW NORMAL TEMPERATURES ARE INDICATED FOR HAWAII FOR LONGER
LEADS.
ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ARE FORECAST OVER ALL
HAWAIIAN ISLANDS, KAUAI, OAHU, MAUI AND THE BIG ISLAND, FOR THE ASO THREE-MONTH
SEASON AND FOR THE BIG ISLAND FOR SON 2026 AS WELL, ASSOCIATED IN PART WITH
PREDICTED POSITIVE SST ANOMALIES NEAR THE ISLANDS AND SUMMER EL NINO IMPACTS.
IN SEPTEMBER-OCTOBER-NOVEMBER (SON) 2026, EC IS INDICATED IN THE SEASONAL
PRECIPITATION OUTLOOK FOR KAHULUI, HONOLULU AND LIHUE, DUE TO WEAKER SIGNALS IN
FORECAST TOOLS. BELOW NORMAL PRECIPITATION IS INCREASINGLY LIKELY FOR ALL OF
HAWAII BEGINNING IN OND 2026 AND CONTINUING THROUGH THE FEBRUARY-MARCH-APRIL
(FMA) 2027 SEASON, DUE TO THE HISTORICAL RELATIONSHIP FOR THE HAWAIIAN ISLANDS
BETWEEN A PREDICTED STRONG EL NINO EVENT AND WINTER PRECIPITATION. THE OUTLOOK
IS SUPPORTED BY DYNAMICAL MODEL FORECASTS THROUGH DJF 2026-27 AND BY THE CA
THROUGH FMA 2027. DUE TO UNCERTAINTY IN FORECASTS FOR LONGER LEADS FOLLOWING
THE FMA 2027 SEASON, EC IS INDICATED FOR THE PRECIPITATION OUTLOOK.
HILO
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
ASO 2026 A75 76.4 0.4 A50 26.1 28.8 33.3
SON 2026 A70 76.2 0.4 A40 24.3 30.2 40.8
OND 2026 A65 75.5 0.4 B40 28.3 34.5 42.0
NDJ 2026 A60 74.2 0.4 B55 26.4 36.6 43.0
DJF 2027 A40 72.8 0.4 B65 19.6 30.2 33.3
JFM 2027 EC 71.8 0.4 B60 22.0 32.0 44.5
FMA 2027 EC 71.7 0.4 B50 24.6 34.1 45.5
MAM 2027 EC 72.0 0.5 EC 22.5 28.4 34.0
AMJ 2027 EC 72.9 0.5 EC 21.4 23.7 29.0
MJJ 2027 EC 74.0 0.4 EC 20.2 27.5 29.1
JJA 2027 EC 75.2 0.4 EC 19.4 27.2 31.4
JAS 2027 EC 76.1 0.4 EC 25.2 28.6 33.4
ASO 2027 EC 76.4 0.4 EC 26.1 28.8 33.3
KAHULUI
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
ASO 2026 A75 79.4 0.4 A40 0.8 1.6 2.5
SON 2026 A70 79.1 0.4 EC 2.1 3.3 4.8
OND 2026 A60 77.8 0.4 B40 4.2 5.3 8.1
NDJ 2026 A50 75.9 0.4 B50 5.2 7.6 9.5
DJF 2027 EC 73.8 0.4 B60 4.6 6.9 8.7
JFM 2027 EC 72.5 0.4 B55 4.2 6.2 8.2
FMA 2027 EC 72.3 0.4 B45 3.2 4.1 6.4
MAM 2027 EC 73.0 0.4 EC 2.5 3.5 4.6
AMJ 2027 EC 74.3 0.5 EC 1.2 1.6 2.2
MJJ 2027 EC 76.0 0.5 EC 0.7 1.1 1.8
JJA 2027 EC 77.7 0.4 EC 0.7 1.1 1.5
JAS 2027 EC 79.0 0.4 EC 0.8 1.1 1.6
ASO 2027 EC 79.4 0.4 EC 0.8 1.6 2.5
HONOLULU
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
ASO 2026 A70 81.7 0.4 A40 1.6 2.4 3.1
SON 2026 A70 81.4 0.4 EC 2.5 4.0 5.6
OND 2026 A55 80.0 0.4 B40 4.4 6.4 8.5
NDJ 2026 A40 77.7 0.5 B50 3.9 5.6 8.8
DJF 2027 EC 75.3 0.5 B60 3.7 5.6 8.6
JFM 2027 EC 73.9 0.4 B55 2.1 4.6 7.8
FMA 2027 EC 73.8 0.4 B45 1.9 3.2 4.7
MAM 2027 EC 74.8 0.4 EC 1.8 2.6 3.0
AMJ 2027 EC 76.3 0.4 EC 1.2 1.6 1.8
MJJ 2027 EC 78.2 0.4 EC 0.8 1.4 1.6
JJA 2027 EC 79.9 0.4 EC 0.7 0.8 1.3
JAS 2027 EC 81.3 0.4 EC 1.0 1.4 1.7
ASO 2027 EC 81.7 0.4 EC 1.6 2.4 3.1
LIHUE
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
ASO 2026 A70 79.4 0.3 A40 6.2 7.9 8.4
SON 2026 A60 79.1 0.3 EC 9.2 10.0 11.2
OND 2026 A50 77.8 0.3 B40 9.2 11.7 15.6
NDJ 2026 EC 75.7 0.3 B50 8.6 12.1 16.9
DJF 2027 EC 73.6 0.4 B60 7.5 8.4 14.0
JFM 2027 EC 72.2 0.4 B55 6.5 8.8 13.8
FMA 2027 EC 72.1 0.5 B45 5.8 8.4 9.9
MAM 2027 EC 72.8 0.5 EC 5.3 6.6 8.0
AMJ 2027 EC 74.2 0.5 EC 4.7 5.5 6.0
MJJ 2027 EC 76.0 0.5 EC 4.9 5.4 5.9
JJA 2027 EC 77.7 0.4 EC 4.4 5.3 6.9
JAS 2027 EC 79.0 0.3 EC 5.3 6.1 7.8
ASO 2027 EC 79.4 0.3 EC 6.2 7.9 8.4
FORECASTER: DAN COLLINS
ANOMALIES ARE BASED ON THE 1991-2020 MEANS.
CLARIFICATION: EC INDICATED EQUAL CHANCES THAT THE PREDICTED PARAMETER WILL
FALL INTO ANY ONE OF THE THREE CATEGORIES, WHOSE BOUNDARIES ARE SPECIFIC IN THE
TABLES ABOVE. A FORECAST SPECIFICATION OF EC MEANS THERE IS NO PARTICULATE TILT
OF THE ODDS TOWARD ABOVE NORMAL OR BELOW NORMAL CONDITIONS IN THE OUTLOOK. FOR
EXAMPLE A40 MEANS A 40% CHANCE THAT THE AVERAGE TEMPERATURE OR TOTAL
PRECIPITATION WILL BE IN THE ABOVE NORMAL CLASS, B40 MEANS A 40% CHANCE THAT
THE AVERAGE TEMPERATURE OR TOTAL PRECIPITATION WILL BE IN THE BELOW NORMAL
CLASS, AND N35 MEANS A 35% PROBABILITY THAT THE AVERAGE TEMPERATURE OR TOTAL
PRECIPITATION WILL BE IN THE NEAR NORMAL CLASS. WHEN EC IS SPECIFIED, ALL
CATEGORIES ARE EQUALLY LIKELY.
NOTE - THESE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THE VALID
PERIODS. WITHIN ANY VALID PERIOD, OBSERVATIONS AND SHORTER RANGE FORECASTS
SHOULD BE CONSULTED. ALSO, THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE
ISSUANCES OF THE NEW SET NET MONTH, ON THU AUG 20, 2026.
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