Hier, la NOAA a publié ses perspectives mensuelles pour septembre 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: Septembre 2025 devrait être plus chaud et plus sec que la normale dans une grande partie des Rocheuses et de Mountain West, réduisant les chances de neige en début de saison, tandis que certaines parties du sud-est et de l'Alaska verront un temps plus humide, mais il est toujours peu probable qu'il obtienne une neige importante. Les skieurs et les snowboarders devraient anticiper un début lent à la saison des neiges américaines.
Faits saillants de la température
Plus chaud que la normale:
Conditions typiques:
Présentation des précipitations
Plus sèche que la normale:
Plus humide que la normale:
Perspectives moyennes:
Potentiel de neige pour septembre
Alors que septembre est encore très tôt pour la neige généralisée dans la plupart des régions de ski, les poches des hautes rochers et les cascades obtiennent parfois leurs premières poussières. Cette année, cependant, les prévisions de conditions plus chaudes et plus sèches dans ces zones suggèrent peu de neige naturelle, nous devrons donc attendre d'octobre pour un début de saison plus significatif. Si vous espérez des virages anticipés, les meilleurs paris seront dans les altitudes les plus élevées et dans des régions comme l'Alaska ou les montagnes du sud-est, où les précipitations seront au-dessus de la normale, même si celles-ci verraient plus probablement la pluie que l'accumulation de neige ce mois-ci.
En résumé
Attendez-vous à des conditions douces et sèches dans une grande partie de la montagne ouest, avec des perspectives limitées de neige skiable précoce. Le sud-est et l'Alaska pouvaient voir un temps plus humide, mais les températures chaudes rendent toujours la neige rare. Gardez un œil sur les sommets élevés et restez à l'écoute pour toutes les surprises fraîches.
Septembre 2025 Outlook Discussion complète
30-DAY OUTLOOK DISCUSSION FOR SEPTEMBER 2025 El Niño Southern Oscillation (ENSO) neutral conditions are present with sea surface temperatures (SSTs) near average across most of the equatorial Pacific Ocean. The Madden-Julian Oscillation (MJO) is currently characterized by its enhanced convective phase crossing the Indian Ocean, with the bulk of the associated tropical rainfall located over the Maritime Continent region. The latest MJO forecasts from dynamical models indicate considerable uncertainty in the expected evolution of the MJO during the next several weeks. The September 2025 Temperature and Precipitation Outlooks are based on a combination of dynamical models , including CFSv2, the North American Multi-Model Ensemble (NMME), the Copernicus Climate System (C3S), and to a lesser extent statistical models/tools such as the Canonical Correlation Analysis (CCA), Constructed Analog on Soil moisture (CAS), Optimal Climate Normals (OCN), and a combined ENSO-OCN tool. The monthly outlooks are also based on dynamical models and statistical tools for the Weeks 3-4 period which cover the early and middle thirds of September. Uncertainty regarding the evolution of the MJO precluded its use as a viable tool in the construction of the September outlook. Impacts from the MJO will be re-evaluated at the end of the month for the updated version of this Outlook. Local SSTs and antecedent soil moisture anomalies also contributed to this outlook where applicable. The September 2025 Temperature Outlook favors above-normal temperatures across most of the Contiguous United States (CONUS). The regions of highest probabilities (reaching 60 to 70%) are located over the upper Four Corners/central Rockies area and over New England. For the former region over the West which includes a broader 50-60% area encompassing much of the Interior West, Rockies, and southern High Plains, the outlook is consistent with a majority of the dynamical and statistical tools. A somewhat broader 50-60% area is also favored over most of the Northeast, based on many of the dynamical models/tools, historical trends (as indicated by the OCN tool), and to some extent the proximity of relatively warm coastal waters of the western Atlantic. Elsewhere, probabilities favoring above-normal temperatures are elevated (50-60%) over most of the Florida Peninsula, based on various tools and a strong trend signal. From the north-central CONUS to the Gulf and Southeast coasts (excluding Florida), discrepancies between models and comparatively weaker overall warm signals compared to other portions of the CONUS call for modest probabilities tilting toward above-normal temperatures (33-40%). For the coast of southern California, Equal Chances (EC) of above, near, and below-normal temperatures are favored due to the proximity of near to below-normal sea-surface temperatures (SSTs) near the coast. In Alaska, above-normal temperature chances are elevated over the western and southern Mainland, the Alaska Peninsula and eastern Aleutians, and Southeast Alaska. This is largely attributed to the calibrated C3S tool, persistence of the area of agreement between the ECMWF and GEFS Weeks 3-4 temperature tools, and relatively warm coastal SSTs. The higher chances for above-normal temperatures (50-60%) over northwestern portions of the Mainland are based on historical trends that favor a delay in the onset of sea ice formation. For the remainder of the Mainland and the western Aleutians, EC is favored. The September 2025 Precipitation Outlook favors elevated odds of above-normal precipitation from the eastern Gulf region (including Florida) across the Southeast and Mid-Atlantic coast. Much of the dynamical and statistical guidance warrants these elevated odds of above-normal precipitation, as does the climatological peak of Atlantic tropical cyclone activity in September. In addition, this enhanced wet signal is consistent with an increased likelihood of stalled fronts. For the Pacific Northwest, some (but not all) of the tools support increased chances of above-normal precipitation, with September being the climatological transition month from dry to wet season. From most of the Interior West, Rockies, High Plains, extending eastward into the Ozarks odds favor below-normal precipitation, with maximum probabilities of 50-60% over a sizable multi-state area centered near the Great Salt Lake in northern Utah. To varying degrees this is based on the NMME Consolidation, the CFSv2, and a few constituent models of the C3S suite. The eastward extension of the relative dryness across the south-central Plains and Ozarks area is based on recent soil moisture anomalies. However, probabilities are modest given the uncertainty in how much precipitation may fall over this region in September. Over far southern portions of the Southwest a token EC is indicated due to the possibility of a gulf surge or a recurving east Pacific hurricane bringing precipitation into this area during the month of September. Well to the north, above-normal precipitation is slightly favored over Southeast Alaska. Due to conflicting indications among the dynamical and statistical models/tools, this outlook for Alaska is based on persistence of the Weeks 3-4 precipitation signals from the CFS, GEFS, and ECMWF models, the 30-day uncalibrated C3S, the Meteo-France model, and the proximity of relatively warm SSTs. For the remainder of Alaska, EC is favored for the precipitation outlook.
