A G3 – Strong geomagnetic storm watch is in effect following a powerful M8.1 solar flare from geoeffective Active Region 4299 at 20:39 UTC on December 6, 2025. The resulting full-halo coronal mass ejection (CME) is expected to impact Earth between early and midday UTC on December 9, possibly producing periods of strong geomagnetic storming.
A strong and shallow earthquake registered by the USGS as M7.0 struck near Yakutat, Alaska, at 20:41 UTC on December 6, 2025. The agency is reporting a depth of 10 km (6.2 miles). EMSC is reporting M6.8 at a depth of 10 km. According to the National Tsunami Warning Center (NTWC), there is no tsunami danger from this earthquake.
A strong solar flare measuring M8.1 erupted from Active Region 4299 at 20:39 UTC on December 6, 2025. The event started at 20:29 and ended at 20:49 UTC. A full-halo coronal mass ejection was produced, with impact expected early to midday on December 9, potentially causing periods of G3 – Strong geomagnetic storming.
A major atmospheric river (AR4–AR5 possible) is forecast to make landfall over the Pacific Northwest early Monday, December 8, 2025, and persist through Wednesday, December 10, bringing multiple days of heavy rain and elevated snow levels. Ensemble guidance shows ~70–80% of members reaching at least AR4 in southern coastal Washington, with ~20–30% indicating AR5, raising the risk of widespread riverine flooding.
Three atmospheric rivers (ARs) are forecast to make landfall over the Pacific Northwest (PNW) through December 10, 2025, producing prolonged precipitation and high moisture transport across western Washington and Oregon.
The polar vortex is forecast to settle near Hudson Bay, sending repeated waves of Arctic air into the central and eastern U.S. during the first half of December 2025.
The season’s first nor’easter began impacting the Mid-Atlantic and Northeast overnight, prompting a State of Emergency in parts of New Jersey and school closures across multiple states. The storm is forecast to rapidly intensify, possibly dropping up to 30 cm (12 inches) of snow across parts of the interior Northeast through Tuesday.
Over 1 000 people have died and hundreds remain missing on Tuesday, December 2, 2025, after rare Tropical Cyclone Senyar brought severe flooding and landslides across Indonesia, Thailand, and Malaysia.
NOAA’s Space Weather Prediction Center (SWPC) issued a G2 – Moderate geomagnetic storm watch for December 3 and 4, 2025, following a coronal mass ejection (CME) associated with the X1.9 solar flare from Active Region 4299 on December 1. The CME is expected to deliver a glancing blow to Earth’s magnetic field, coinciding with a co-rotating interaction region (CIR) and a sector boundary crossing, increasing the potential for moderate geomagnetic storming and visible auroras at mid-latitudes.
The first nor’easter of the season is forecast to rapidly intensify by Wednesday, December 3, 2025, bringing 25–38 cm (10–15 inches) of snow, violent winds, and whiteout conditions across parts of the U.S. Northeast and Nova Scotia, and Newfoundland, Canada.
