WeatherNext 3 Is Operational—but the Managed Inference Page Still Specifies WeatherNext 2
AccessAllGPT reviewed Google’s September 3 launch, the 43-page WeatherNext 3 paper, the WeatherNext developer overview, benefits-and-limitations guide and managed-inference specification, plus Brightband’s independent Operational WeatherBench leaderboard and methodology, retrieved 2026-09-04. We downloaded the paper, recorded SHA-256 12563b139a446fa2c8ac0f1e72753ce5ab9029bc505ef08237cd9a7ffca7b726, and extracted all 43 pages with pypdf 6.0.0 under Python 3.11.15. We wrote and ran scripts/audit-weathernext3-contract.mjs on Node v24.10.0, Darwin arm64 to fetch six live artifacts, assert the hourly/64-member operational contract, the WeatherNext 2 managed-inference boundary, documented artifacts and independent leaderboard presence, and hash each response. We did not have Google Cloud credentials or download forecast arrays, so this is a public-artifact and access-contract audit—not a forecast-skill reproduction.
WeatherNext 3: Increasing resolution and performance of global weather models with raw observations
Google DeepMind and Google Research · RetrievedReviewed: Abstract; model architecture; inputs and targets; evaluation methodology; results; joint forecast artifacts; discussion; disclaimer; appendices
Supports: The 43-page paper describes a 15-day, 64-member FGN ensemble with hourly initialization, mixed 0.1° and 0.25° grids, a 0.05° station head, satellite inputs, evaluation windows and baselines. It also discloses precipitation caps, limited real-time sampling, mesh artifacts, six-hour boundary jumps, cyclone under-spread and experimental-use warnings.
Introducing WeatherNext 3, our most advanced and accurate global weather AI model
Google · RetrievedReviewed: September 3 launch date; architecture diagram; resolution and cadence; satellite ingestion; product integrations; model access; claimed evaluations
Supports: Google announced WeatherNext 3 on September 3, 2026, describing hourly refreshes, up-to-5-kilometer output, direct geostationary-satellite input and integrations across Search, Gemini, Maps, Google Maps Platform and Cloud. These capability and superiority statements are vendor claims unless separately corroborated.
WeatherNext developer overview
Google for Developers · RetrievedReviewed: WeatherNext 3 operational summary; forecast-data access; custom inference; open-source positioning; Weather Lab; product navigation
Supports: The overview says WeatherNext 3 provides 15-day probabilistic forecasts initialized hourly across 64 members and exposes operational forecasts through Cloud Storage Zarr, Earth Engine and BigQuery. It separately advertises custom inference and open-source research models without saying the WeatherNext 3 production checkpoint or training code is downloadable.
WeatherNext benefits and limitations
Google for Developers · RetrievedReviewed: Accuracy; ensembles; speed; resolution; precipitation; downstream use; reanalysis bias; smoothing; artifacts; temporal discontinuities; per-member bias
Supports: Google documents WeatherNext 3 resolution and output benefits but also says individual samples can show mesh artifacts, experimental precipitation-head hexagons, six-hour station-head jumps and changing per-sample global bias. It points custom ensemble sizing to WeatherNext 2 managed inference rather than WeatherNext 3.
Model specifications and data schema
Google for Developers · RetrievedReviewed: Managed model identity; architecture; spatial and temporal resolution; initialization; horizon; training data; output ensemble; schema; update date
Supports: The managed-inference specification explicitly says the model accessible on Gemini Enterprise Agent Platform is WeatherNext 2. It documents a 0.25° model initialized every six hours, despite the adjacent site now presenting WeatherNext 3 as the flagship operational data product.
Operational WeatherBench methodology
Brightband · RetrievedReviewed: Models; verification targets; deterministic and probabilistic metrics; aggregation; lead times; WeatherNext 3 notes; licensing and references
Supports: Brightband independently includes WeatherNext 3 in a live leaderboard computed with WeatherBench-X. Its methodology says WeatherNext 3 is initialized from ECMWF IFS analysis and therefore uses IFS analysis as the substituted verification target; this is operational corroboration with an important target-comparability caveat.
Operational WeatherBench live leaderboard
Brightband · RetrievedReviewed: Latest ranked cycle; active streak; ranking selector; regional leaders; scorecard, skill and time-series navigation; live-status labeling
Supports: At retrieval, Brightband displayed a latest ranked cycle of August 26, 2026 12Z, identified WeatherNext 2 Mean as the three-cycle active streak, and listed WeatherNext 3 as regional leader in several links. The live page corroborates evaluation availability but is mutable and does not establish universal superiority.