Latest News
12/16/2025, 5:46 am EST
An important climate diagnostic, missing since last April, has returned this month: Multivariate ENSO index (MEI). The MEI identifies the response of the atmosphere (30S to 30N) to the Pacific equatorial sea surface temperature anomaly (SSTA) regime. Note that the conventional climate diagnostic to identify ENSO phase, the Nino34 SSTA, only recently shifted to La Nina. A La Nina regime is indicated by MEI all but APR and MAY of the past 12 months.
12/12/2025, 9:49 am EST
Upper trough maintains the Mediterranean Sea storm track in late December/early January. North of the storm track, colder east wind from Russia develops. However, dry pattern prevents any snow gain.
12/11/2025, 8:29 am EST
Wet weather continues to emerge and intensify across Brazil. The rainfall is making a difference in soil moisture as East Brazil loses their wet signature. Additional heavy to excessive rainfall is on the way!
12/10/2025, 11:56 am EST
The DEC-25 U.S. gas population weight HDD is revised colder to 949, the coldest DEC since 2010 and 3rd coldest of this century. Previously, cold JAN-26 forecasts reversed warmer with mid-NOV updates and then colder with the early DEC projection. Operational models are shifting much warmer for JAN-26 therefore a warmer revision is necessary. The JAN-26 HDD forecast warms from 981 to 947 which ranks 13th coldest of 2020-25.
12/09/2025, 4:55 am EST
La Nina has recently weakened. Some regeneration is possible for later this month/early January. However, the push toward warming by a recent intense MJO event suggests the weak late 2026 La Nina has peaked, and neutral ENSO generates for Q1/2026. The warming Northeast Pacific generated in-part by the recent intense MJO event requires monitoring. Often, warming of the Northeast Pacific is a precursor to an ENSO phase change toward El Nino. ECMWF and NMME (models) forecast El Nino onset during Q2/2026.
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When Does The Stratosphere Warm Again?
The stratospheric warming event of mid-November to mid-December is dissipating. The warming event took place on the American side of the North Pole and spawned a polar vortex in North America causing the early meteorological winter 2025-26 arctic outbreak across the eastern states. Forecast models indicate the cold stratosphere across Eurasia expands cross-polar into North America later this month.
Climate Impact Company Climate Diagnostics
Historical Precipitation Event Ahead West U.S. – Causes and Implications
The 2025-26 cold season is barely underway and already two dramatic weather regimes are identified: 1.) The just-ending arctic outbreak across the East U.S. and 2.) The evolving excessive precipitation event for the West Coast lasting the remainder of December and into January.