490 FXUS05 KWBC 181230 PMD90D Prognostic Discussion for Long-Lead Seasonal Outlooks NWS Climate Prediction Center College Park MD 830 AM EDT Thu Sep 18 2025 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS Sea surface temperatures (SSTs) are currently near-to-below average across the central and eastern equatorial Pacific Ocean. The ENSO Alert System Status continues with a La Nia Watch, which is issued when conditions are favorable for the development of La Nia within the next 6 months. A transition from ENSO-neutral to La Nia is likely in the next couple of months, with a 71% chance of La Nia during October-November-December (OND) 2025. Thereafter, La Nia is favored but chances decrease to 54% in December-January-February (DJF) 2025-26, with ENSO-neutral expected to return by late winter and spring. The October-November-December (OND) 2025 Temperature Outlook favors above-normal temperatures over most of the Contiguous U.S. (CONUS), with the exception of Equal Chances (EC) of above, near, and below-normal temperatures forecast from the Pacific Northwest eastward across the northern tier to the Upper Great Lakes region. Probabilities favoring above-normal temperatures range from 50-60% over the Four Corners region and West Texas, the Northeast, and southern Florida, and peak at 60-70% over New Mexico and parts of neighboring states. Above-normal temperatures are also favored over much of Alaska, excluding east-central and Southeast Alaska, where EC is indicated. The October-November-December (OND) 2025 Precipitation Outlook favors above-normal precipitation over much of the Florida Peninsula, the Pacific Northwest eastward to the Northern High Plains, and most of the western half of Alaska. Below-normal precipitation is favored over much of the southern CONUS. Elsewhere over the U.S., EC is forecast where probabilities for each category of seasonal mean temperatures and seasonal accumulated precipitation amounts are expected to be similar to climatological probabilities. BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS Note: For Graphical Displays of the Forecast Tools Discussed Below See: http://www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS ENSO-neutral continued in August 2025, with near-to-below average SSTs observed across the central and eastern equatorial Pacific. The latest weekly Nio 3.4 SST index is -0.5 C. Negative subsurface temperature departures (averaged from 180-100W) strengthened, with below-average temperatures prevailing from the surface to a depth of 200m in the central and eastern Pacific. Relatively warm surface and subsurface water temperatures are confined to the far western tropical Pacific. Low-level wind anomalies were easterly across most of the equatorial Pacific, while upper-level wind anomalies were westerly over the western and eastern equatorial Pacific. Deep tropical convection was enhanced over Indonesia and the Maritime Continent region, and suppressed near the Date Line. The current state of the coupled ocean-atmosphere system reflected the continuation of ENSO-neutral. As for local impacts, local SSTs are above-average in the coastal waters surrounding most of Alaska, along the West Coast of the CONUS, and the Gulf and Southeast coasts. Cooler-than-normal waters are observed off the Upper Mid-Atlantic and Northeast coasts. Local interaction between soil moisture and temperature and precipitation declines significantly as the growing season draws to a close. The CPC Leaky Bucket model depicts below-average soil moisture over much of the western U.S., the Middle and Lower Mississippi Valley, Ohio Valley, Northeast, Mid-Atlantic, and Florida, with scattered regions of above-average soil moisture over the Upper Mississippi Valley, much of the Great Plains, and a portion of the Southeast. Local interactions with soil moisture and SSTs are considered for early leads where applicable and relevant. PROGNOSTIC DISCUSSION OF SST FORECASTS The North American Multi-Model Ensemble (NMME) favors a short-lived La Nia during fall and early winter 2025-26. The CPC Nio 3.4 SST Index favors a minimal to weak La Nia from the SON season through January-February-March (JFM) 2026. In contrast, predictions from the International Research Institute (IRI) favor ENSO-neutral to persist through fall and winter 2025-26. This current set of seasonal outlooks is going with a transitional lead-1 period (OND 2025), followed by a weak La Nia for leads 2-4 (NDJ 2025-26 through JFM 2026), with ENSO-neutral re-emerging during leads 5-6 (FMA to MAM 2026). PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS Dynamical model forecasts from the NMME, the Coupled Forecast System Model Version 2 (CFSv2), and the Copernicus (C3S) multi-model ensemble system were used extensively for the first six leads when they are available, as was the objective, historical skill weighted consolidation and Calibration, Bridging, and Merging (CBaM) guidance, that combines both dynamical and statistical forecast information. A consolidation of statistical tools including the ENSO-OCN tool, which represents the combined influence of ENSO (when active) and decadal timescale trends in temperature and precipitation (utilizing the Optimum Climate Normal, OCN) and dynamical models is used for the first six leads. Following this, the ENSO-OCN forecast tool is used more extensively. Decadal variability and trends are determined from the OCN, representing the difference between the most recent 15-year period average seasonal temperature or precipitation and the average for the climatology period, from 1991-2020. La Nia temperature and precipitation historical composites were used for the NDJ 2025-26, DJF 2025-26, and JFM 2026 seasons. PROGNOSTIC DISCUSSION OF OUTLOOKS - OND 2025 TO OND 2026 TEMPERATURE For the OND 2025 Temperature Outlook, above-normal temperatures are favored over most of the Contiguous U.S. (CONUS), with the exception of EC from the Pacific Northwest eastward across the northern tier to the Upper Great Lakes region. Probabilities favoring above-normal temperatures range from 50-60% over the Four Corners region and West Texas, the Northeast, and southern Florida, and peak at 60-70% over New Mexico and parts of neighboring states. Above-normal temperatures are also favored over much of Alaska, excluding east-central and Southeast Alaska, where EC is indicated. The widespread coverage of favored above-normal temperatures is consistent with most dynamical and statistical model guidance and with trends. Relatively warm SSTs are a partial contributor to the widespread anomalous warmth. In northwestern Alaska, probabilities of above-normal temperatures reach 50-60%, tied to the climatological delay in the onset of sea ice in that region. In sharp contrast to this, the NCAR_CESM1 and NCAR_CCSM4 models forecast below-normal temperatures for most of the state of Alaska. The SST-CA tool (Constructed Analog using SST anomalies) forecasts a relatively cold Southeast Alaska during OND 2025. For leads 2-6 (NDJ 2025-26 through MAM 2026), the temperature outlooks are consistent with the predicted onset, occurrence, and decay of La Nia. The CPC-IRI consensus forecast predicts the La Nia will transition to ENSO-neutral sometime during the JFM 2026 season, while the CPC ENSO 3.4 SST Consolidation forecast shows the re-emergence of ENSO-neutral by FMA 2026. From NDJ through MAM, an initially small area of favored below-normal temperatures over western Washington expands eastward with time to include parts of the Northern Rockies, Northern Plains, and Minnesota culminating in peak spatial coverage during FMA 2026. By MAM, only a small remnant of favored below-normal temperatures is depicted along the border between the Northern Plains and the Canadian provinces of Saskatchewan and Manitoba. The large area of favored above-normal temperatures during the OND season is predicted to gradually shrink and recede southward and eastward during the late fall and early winter to a relative minimum during JFM/FMA 2026. By that time, favored above-normal temperatures are predicted to be limited to the far southern and far eastern portions of the CONUS. By MAM 2026 and beyond, the area of favored anomalous warmth is predicted to expand once again northward and somewhat westward to include nearly all of the CONUS by next fall (SON and OND 2026). The temperature outlooks at these leads (from MAM 2026 onwards) are largely based on historical long-term trends. During most of these seasons, the greatest chance of above-normal temperatures (50-60%) is indicated over the West, the Northeast, and the general vicinity of Florida. For Alaska, the combination of dynamical and statistical models, and trends, favored above-normal temperatures for much of western and northern Alaska throughout the fall and winter. The most likely area to register below-normal temperatures during the next 6 months is Southeast Alaska and adjacent portions of south-central Alaska, from DJF 2025-26 through FMA 2026, based on La Nia composites and to some degree, numerical model guidance. From spring 2026 onwards, the Alaska temperature outlooks are dominated by long-term historical trends. PRECIPITATION For the OND 2025 Precipitation Outlook, above-normal precipitation is favored over much of the Florida Peninsula, the Pacific Northwest eastward to the Northern High Plains, and most of the western half of Alaska. The wet signal across Florida is partly due to the time of year, as tropical cyclones occasionally form in the Caribbean Sea or Gulf of America and track northeastward or eastward across the state. This is supported by the calibrated C3S, and some of the models that comprise the C3S ensemble system. The northwestern CONUS wet signal (especially over the interior) is consistent with many of the dynamical and statistical tools, and is related to the expected mean Pacific jet stream position associated with La Nia (especially during the second half of this season), and the climatological early stages of the rainy season along the West Coast. The wetter-than-normal conditions favored over most of the western half of Alaska are supported by much of the NMME and C3S model guidance and relatively warm SSTs surrounding most of the state. This pattern is also commonly observed during cold season La Nias featuring high pressure over the northeastern Pacific and broad onshore flow across the western part of Alaska. Below-normal precipitation is favored over much of the southern CONUS, and this is borne out by a large majority of the guidance. This broad area of favored below-normal precipitation extends over the western Gulf Coast region and the interior Southeast, related to a seasonal tendency for westerly winds to become more dominant in this region, and the preference for any tropical cyclones to be shunted eastward and northeastward across Florida and the western Atlantic. Elsewhere over the CONUS and Alaska, no single tercile class is favored over another, so EC is indicated. As we move forward into the late fall and winter, La Nia precipitation composites and regressions were also consulted, in addition to the usual dynamical and statistical model guidance. For leads 2-4 (NDJ 2025-26 through JFM 2026), which coincides with the peak of a predicted weak La Nia), the area of favored above-normal precipitation across the Northwest generally shifts and/or expands eastward, while a new wet signal (i.e. an area of above-normal precipitation) is favored to develop over the Central and Southern Great Lakes region in NDJ, and expand south-southwestward to the Lower Mississippi Valley through FMA 2026. Drier-than-normal conditions are favored during this same period (NDJ through JFM) across a large portion of the southern tier of the CONUS, with slightly elevated probabilities depicted over the Southwest/California and portions of the Southeast. This is generally supported by many of the tools, such as the calibrated versions of the C3S and NMME, CBaM, and La Nia historical composites. The Alaska precipitation outlooks for this same period tilt the odds towards above-normal precipitation for much of the state, excluding Southeast Alaska and the central and western Aleutians. This is consistent with many of the tools, such as the calibrated NMME and C3S, CBaM, the consolidations, and to some degree, trends. For leads 5-6 (FMA and MAM 2026), the favored wet signals in the Northwest and east-central CONUS are predicted to weaken and disappear with time, with only a single wet signal remaining in MAM over the vicinity of the Upper Mississippi Valley and surrounding areas. The relative dryness over the southern CONUS is forecast to split into two components; one over the Southwest and one over the Southeast in FMA, with only the Southwest dry signal lingering into MAM. Alaskas wet signal is forecast by some model guidance to shrink back to northwestern Alaska by MAM 2026. From lead 7 (AMJ 2026) onward, the precipitation signals are generally consistent with long-term trends as depicted by the OCN tool. During leads 7-10, a tilt towards below-normal precipitation is favored for the northwestern part of the CONUS, and a tilt towards above-normal precipitation is favored for parts of the East. The wet signal in the East continues through lead 11 (ASO 2026), while the dry signal in the northwestern CONUS gradually fades and splits into two areas of slightly favored below-normal precipitation; one over the Southwest and the other over the Upper Mississippi Valley. By lead 13 (OND 2026), trends also favor the reappearance of a dry signal over the western Gulf Coast region. FORECASTER: Anthony Artusa The Climatic normals are based on conditions between 1991 and 2020, following the World Meterological Organization convention of using the most recent 3 complete decades as the climatic reference period. The probability anomalies for temperature and precipitation based on these new normals better represent shorter term climatic anomalies than the forecasts based on older normals. For a description of of the standard forecast tools - their skill- and the forecast format please see our web page at http://www.cpc.ncep.noaa.gov/products/predictions/long_range/tools.html (Use Lower Case Letters) Information on the formation of skill of the CAS forecasts may be found at: http://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Outlook/outlook.shtm l (use lowercase letters) Notes - These climate outlooks are intended for use prior to the start of their valid period. Within any given valid period observations and short and medium range forecasts should be consulted. This set of outlooks will be superseded by the issuance of the new set next month on Oct 16 2025 1991-2020 base period means were implemented effective with the May 20, 2021 forecast release. $$