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FXHW40 KWBC 171231
PMDHCO
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THU SEP 17 2026
MONTHLY FORECAST DISCUSSION VALID OCTOBER 2026
SEA SURFACE TEMPERATURE (SST) ANOMALIES RANGING FROM -0.5 TO +0.5 DEGREES
CELSIUS (C) WERE OBSERVED AROUND THE HAWAIIAN ISLANDS (KAUAI, OAHU, MAUI AND
THE BIG ISLAND) DURING THE PREVIOUS WEEK .
FROM JANUARY THROUGH AUGUST 2026, RAINFALL TOTAL ACCUMULATIONS WERE:
LIHUE AIRPORT 39.79 INCHES (180 PERCENT OF AVERAGE)
HONOLULU AIRPORT 22.03 INCHES (230 PERCENT OF AVERAGE)
KAHULUI AIRPORT 29.68 INCHES (288 PERCENT OF AVERAGE)
HILO AIRPORT 108.24 INCHES (144 PERCENT OF AVERAGE)
MOST CLIMATE MODELS FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND THE
INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME/C3S) PREDICT POSITIVE SST ANOMALIES
AROUND THE HAWAIIAN ISLANDS IN OCTOBER 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 OCTOBER 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 FROM THE NMME AND IMME.
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
HILO A70 75.7 0.5 A55 7.8 8.6 12.1
KAHULUI A70 78.2 0.4 A50 0.3 0.6 1.1
HONOLULU A60 80.2 0.5 A45 0.5 1.3 1.9
LIHUE A50 78.1 0.3 A40 2.5 3.3 4.2
SEASONAL FORECAST DISCUSSION VALID OND 2026 - OND 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.
EL NINO CONDITIONS ARE OBSERVED OVER THE TROPICAL PACIFIC OCEAN. EQUATORIAL SEA
SURFACE TEMPERATURES (SSTS) ARE ABOVE AVERAGE ACROSS THE EAST-CENTRAL AND
EASTERN PACIFIC OCEAN. ABOVE-AVERAGE SUBSURFACE TEMPERATURES HAVE PERSISTED
ACROSS THE EAST-CENTRAL AND EASTERN PACIFIC OCEAN IN THE LAST TWO MONTHS.
ENHANCED CONVECTION AND PRECIPITATION WAS EVIDENT ALONG THE EQUATOR FROM
NEAR THE DATE LINE TO THE EASTERN PACIFIC, WHILE SUPPRESSED CONVECTION AND
PRECIPITATION WAS OBSERVED OVER THE SOUTHERN PHILIPPINES, INDONESIA, AND PAPUA
NEW GUINEA. LOW-LEVEL WESTERLY WIND ANOMALIES WERE EVIDENT FROM THE WESTERN TO
THE EAST-CENTRAL EQUATORIAL PACIFIC OCEAN AND WIND ANOMALIES WERE EASTERLY OVER
THE EASTERN PACIFIC OCEAN. UPPER-LEVEL WIND ANOMALIES WERE EASTERLY FROM THE
WESTERN TO THE EAST-CENTRAL EQUATORIAL PACIFIC AND WESTERLY OVER THE
FAR-EASTERN EQUATORIAL PACIFIC. EL NINO IS STRENGTHENING, WITH A GREATER THAN
90% CHANCE OF A VERY STRONG EVENT DURING THE NORTHERN HEMISPHERE FALL AND
WINTER 2026-27. THE HAWAII SEASONAL OUTLOOK FOR TEMPERATURE AND PRECIPITATION
IS BASED PRIMARILY ON DYNAMICAL MODEL FORECASTS FROM THE NMME AND STATISTICAL
FORECASTS. 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.
ENHANCED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE PREDICTED IN THE
OUTLOOK FOR THE BIG ISLAND FROM OCTOBER-NOVEMBER-DECEMBER (OND) 2026 THROUGH
NOVEMBER-DECEMBER-JANUARY (NDJ) 2026-27, AND FOR OAHU, MAUI, AND KAUAI IN OND.
BELOW-NORMAL TEMPERATURES ARE FORECAST FOR HAWAII ISLANDS FROM
JANUARY-FEBRUARY-MARCH-APRIL (JFM) 2027 THROUGH FEBRUARY-MARCH-APRIL (FMA)
2027, SUPPORTED BY DYNAMICAL MODEL FORECASTS FROM THE NMME AND C3S. EL NINO
IMPACTS TEND TO LEAD TO COOLER-THAN-AVERAGE TEMPERATURES FOR THE NORTHWESTERN
ISLANDS OF HAWAII AS THE WINTER PROGRESSES. DUE TO INCREASING UNCERTAINTY IN
ENSO IMPACTS AND WEAKENING SIGNALS IN FORECAST GUIDANCE, EQUAL CHANCES (EC) FOR
ABOVE, NEAR OR BELOW NORMAL TEMPERATURES ARE INDICATED FOR THE BIG ISLAND IN
DECEMBER-JANUARY-FEBRUARY (DJF) 2027 AND FOR OAHU, MAUI, AND KAUAI FROM NDJ
2026 TO DJF 2026-27. EC IS ALSO INDICATED FOR ALL HAWAIIAN ISLANDS BEGINNING IN
MARCH-APRIL-MAY (MAM) 2027 AND EXTENDING THROUGH LONGER LEADS.
BELOW-NORMAL PRECIPITATION IS INCREASINGLY LIKELY FOR ALL OF HAWAII BEGINNING
IN OND 2026 AND CONTINUING THROUGH THE MARCH-APRIL-MAY (MAM) 2027 SEASON. THIS
IS DUE TO MOST DYNAMICAL AND STATISTICAL SEASONAL PRECIPITATION FORECAST TOOLS
AND THE HISTORICAL RELATIONSHIP BETWEEN A PREDICTED STRONG EL NINO EVENT AND
WINTER PRECIPITATION FOR THE HAWAIIAN ISLANDS. DUE TO UNCERTAINTY IN FORECASTS
FOR LONGER LEADS (FOR THE APRIL-MAY-JUNE (AMJ) 2027 SEASON AND BEYOND), EC IS
INDICATED FOR ALL THE HAWAIIAN ISLANDS FOR THE PRECIPITATION OUTLOOK.
HILO
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2026 A70 75.5 0.4 B60 28.3 34.5 42.0
NDJ 2026 A40 74.2 0.4 B70 26.4 36.6 43.0
DJF 2027 EC 72.8 0.4 B75 19.6 30.2 33.3
JFM 2027 B40 71.8 0.4 B75 22.0 32.0 44.5
FMA 2027 B40 71.7 0.4 B65 24.6 34.1 45.5
MAM 2027 EC 72.0 0.5 B60 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
SON 2027 EC 76.2 0.4 EC 24.3 30.2 40.8
OND 2027 EC 75.5 0.4 EC 28.3 34.5 42.0
KAHULUI
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2026 A60 77.8 0.4 B60 4.2 5.3 8.1
NDJ 2026 EC 75.9 0.4 B70 5.2 7.6 9.5
DJF 2027 EC 73.8 0.4 B75 4.6 6.9 8.7
JFM 2027 B40 72.5 0.4 B75 4.2 6.2 8.2
FMA 2027 B40 72.3 0.4 B65 3.2 4.1 6.4
MAM 2027 EC 73.0 0.4 B60 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
SON 2027 EC 79.1 0.4 EC 2.1 3.3 4.8
OND 2027 EC 77.8 0.4 EC 4.2 5.3 8.1
HONOLULU
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2026 A50 80.0 0.4 B60 4.4 6.4 8.5
NDJ 2026 EC 77.7 0.5 B70 3.9 5.6 8.8
DJF 2027 EC 75.3 0.5 B75 3.7 5.6 8.6
JFM 2027 B40 73.9 0.4 B75 2.1 4.6 7.8
FMA 2027 B40 73.8 0.4 B65 1.9 3.2 4.7
MAM 2027 EC 74.8 0.4 B60 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
SON 2027 EC 81.4 0.4 EC 2.5 4.0 5.6
OND 2027 EC 80.0 0.4 EC 4.4 6.4 8.5
LIHUE
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2026 A50 77.8 0.3 B60 9.2 11.7 15.6
NDJ 2026 EC 75.7 0.3 B70 8.6 12.1 16.9
DJF 2027 EC 73.6 0.4 B75 7.5 8.4 14.0
JFM 2027 B40 72.2 0.4 B75 6.5 8.8 13.8
FMA 2027 B40 72.1 0.5 B65 5.8 8.4 9.9
MAM 2027 EC 72.8 0.5 B60 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
SON 2027 EC 79.1 0.3 EC 9.2 10.0 11.2
OND 2027 EC 77.8 0.3 EC 9.2 11.7 15.6
FORECASTER: LUKE HE
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 OCT 15, 2026.
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