GemAI v3

The latest extended-range weather forecasting model from Salient. Operational and reforecast datasets now available.

0 day
forecasts
0x
daily runs
0
ensemble members
0.00°
spatial resolution
0 year
reforecast

Dataset

16 gridded output variables cover key surface fields and atmospheric dynamics. GemAI v3 goes beyond standard snapshots with native sub-timestep aggregations like min/max temperature, wind gusts, and more. See documentation for details.

🌡️

Temperature

2m instantaneous, plus timestep min, max, and mean; 2m mean dewpoint.

🌧️

Precipitation

Mean precipitation rate and snowfall rate.

💨

Wind

10 m and 100 m mean wind speed; 10 m max gusts; 100 m u/v instantaneous components.

☀️

Radiation & Clouds

Surface downward shortwave flux; total cloud cover.

🌀

Dynamics

Mean sea-level pressure; 500 hPa geopotential.

📈

Climate Modes

ENSO, MJO, QBO, ZMZW, and more (available via API).

🕐

Temporal resolution

6-hourly to day 14; 24-hourly through day 126.

📅

Reforecast schedule

3,443 dates from 2000–2025, 50 ensemble members.

🗜️

Format

Zarr v3 with optimized chunking and compression.

Verification

Medium Range

15-day benchmark CRPS scores against ECMWF ENS, ECMWF AIFS, and Google WeatherNext. Scores computed over 242 dates from July 2025 to March 2026, masked to land areas. GemAI v3 outperforms ECMWF ENS across all variables, is competitive with other state-of-the-art AI models on large-scale dynamics, and achieves best-in-class performance on 2m temperature, particularly the sub-timestep aggregations.

CRPS scorecard: GemAI v3 vs ENS, AIFS, Google WeatherNext across 8 variables

Extended Range

46-day benchmark CRPS scores against ECMWF ENS extended-range and a climatology baseline. Scores computed for 104 dates from July 2023 to July 2025, masked to land areas. GemAI v3 outperforms ECMWF ENS throughout the forecast horizon and retains positive or neutral scores relative to climatology at all leads.

Extended-range CRPS scorecard: GemAI v3 vs ENS Extended and Climatology across 8 variables

Quickstart

Install
pip install "xarray>=2025.6.0" "zarr>=3" "pcodec>=1" s3fs
Python
Python
import xarray as xr

ds = xr.open_zarr(
    "https://gemv3-reforecast.salient-open-data.com/forecast",
    chunks=None,
)
t2m = ds.sel(
    forecast_date="2025-01-01",
    lat=42.36, lon=-71.06, method="nearest",
)["2m_temperature"]
t2m = t2m.assign_coords(valid_time=t2m.forecast_date + t2m.lead
         ).swap_dims(lead="valid_time")
t2m.plot(hue="sample", add_legend=False)

See docs for additional details.

Output
Ensemble spaghetti: 2m temperature at Boston, Jan 2025 GemAI v3 reforecast

Access

Operational

Subscription

Live forecasts from January 2026 onward.

  • 4× daily (00/06/12/18z)
  • 200 ensemble members
  • Available within 6 hours of initialization
  • 126-day horizon on the 00z run
  • Same Zarr format as reforecast
Contact Us