Hier, la NOAA a publié ses perspectives mensuelles pour octobre 2025. Vous trouverez ci-dessous un résumé pour ceux qui ne connaissent pas la terminologie météorologique et la discussion complète plus bas pour ceux qui le sont.
Tl; dr – La plupart des régions de ski américaines peuvent s'attendre à un octobre plus chaud que la normale, avec les meilleures chances de chute de neige en début de saison dans le nord-ouest du Pacifique, les Rocheuses du nord et le sud-est de l'Alaska, grâce à des poches de temps plus humide. Les régions sud et centrales devraient être plus chaudes et plus sèches que d'habitude, donc la neige précoce y est peu probable cette année.
Western aux États-Unis
Central américain
Eastern États-Unis
Alaska
Points clés pour les skieurs et les coureurs
La discussion complète est ci-dessous:
30-DAY OUTLOOK DISCUSSION FOR OCTOBER 2025 The October 2025 temperature and precipitation outlooks considered the evolving state of the El Nino - Southern Oscillation (ENSO), strength and forecast of the Madden-Julian Oscillation (MJO) as well as other coherent subseasonal tropical variability, anomalous land surface conditions (soil moisture, vegetation extent) and both remote and near coastal extratropical sea surface temperatures (SSTs). Dynamical model guidance from the Week 3-4 time period was evaluated and utilized from the ECMWF, GEFS and CFS. Monthly integrations from the NMME and C3S ensemble system suites were also used, both ensemble mean and individual participant model solutions. I note that the SPEAR NMME contributing model continues to be unavailable from NOAA GFDL. The October temperature outlook favors monthly mean above-normal temperatures for much of the country. This includes the western CONUS where forecast guidance, strongly positive temperature trends , large regions of anomalous surface dryness (soil and vegetation) as well as anomalously warm local coastal and greater north Pacific SSTs support this forecast. For southern Texas and the eastern U.S., both statistically and dynamical forecast guidance, positive temperature trends in some areas and in the cas e of the Ohio Valley and mid-South rapidly developing drought conditions lead to the warmer-than-normal forecast. For Alaska, a number of factors at play make the forecast for this region especially challenging this month. Some forecast guidance favors troughing entering October in proximity to the state and so potential below-normal temperatures. But this is offset by above-normal SSTs in many coastal areas around the state as well as quite strong positive temperature trends related to the negative trend in sea ice advance and coverage. For these reasons, an area of favored near-normal monthly mean temperatures is forecast for the west-central coastal areas, while only modest odds for above-normal temperatures are forecast for the north Slope of Alaska and for much of the south coastal areas of the state. For much of the interior portion of the CONUS, Equal-Chances (EC) is forecast as the highest outlook uncertainty is located in this region. In this area, weak short-term climate signals and highly conflicting factors that include dynamical model guidance, soil moisture conditions and uncertain impact from the evolving La Nina state (i.e. La Nina Watch currently in place). For precipitation, the October 2025 outlook is quite conservative due to a number of factors including the time within the overall annual cycle where the signal-to-noise ratio and so forecast predictability is the least. In addition to above, outside of a just a few regions in the U.S., impacts from ongoing climate drivers are generally weak and largely unclear, forecast guidance is strongly conflicted and historical outlook skill for many tools is quite low with poor reliability. Dynamical model guidance during the first 2 weeks of October from Week 3-4 ensemble modeling systems indicates an active pattern for the northeast Pacific and so above-normal monthly total precipitation amounts are favored for the south-central and southeast coastal areas of Alaska and for some areas in the Pacific Northwest and northern Rockies. This is consistent with the Pacific ocean-atmosphere state evolving to a potential La Nina event entering autumn and early winter. During early October, indications from some model guidance for northward shifted westerlies, on average, favor below-normal precipitation for areas of the south-central U.S., lower Mississippi Valley and lower Ohio Valley. This is also consistent with evolving potential La Nina conditions entering fall. Slightly elevated odds for above-normal precipitation is also forecast for the Florida Peninsula and extreme southern Georgia due model guidance suggesting a continuation of a weakness in subtropical ridging in the east-central Gulf of America and associated moisture impacting this area. Also, there is the potential for tropical cyclones or disturbances from the Gulf of America and western Caribbean to impact this area as this moisture can impact far eastern Gulf Coast states and Florida during the month of October. The outlook depicts an above-normal amount of coverage of EC due to some of the factors noted above. These areas include the Southwest, much of the Rockies, northern Plains, Midwest, mid-Atlantic and Northeast. Additional clarity in forecast factors over the next two weeks may allow greater non-EC outlook coverage when the October 2025 updated monthly outlook is released on the last day of September. FORECASTER: Jon Gottschalck The climatic normals are based on conditions between 1991 and 2020, following the World Meteorological Organization convention of using the most recent 3 complete decades as the climate 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. An updated monthly outlook... for Oct will be issued on Tue September 30 2025 These outlooks are based on departures from the 1991-2020 base period. $$
