UK Met Office GloSea6 seasonal forecast maps
UK Met Office GloSea6-GC5.1 seasonal forecast maps (C3S system 610). Compare GloSea6 with ECMWF SEAS5, Météo-France, DWD and CMCC, or compare monthly runs side by side.
GloSea6 is the Met Office Global Seasonal forecasting system. The imported C3S system 610 uses the Global Coupled 5.1 configuration (GloSea6-GC5.1), with the Unified Model atmosphere coupled to land, ocean and sea ice. C3S assigns system 610 to forecasts from April 2026.
GloSea produces two forecast members daily. This site selects the latest 50 members in each nominal monthly C3S ensemble for its probability calculations. The imported hindcasts contain 28 members per reference year: seven for each of four start dates. These are lagged ensembles, so a nominal monthly initialization does not mean that every member began on the first day.
Met Office system identifiers can also change when on-the-fly hindcasts are refreshed annually, without a new model configuration. Forecasts must be paired with the hindcasts for their own identifier.
Configuration source: UK Met Office C3S contribution documentation. Identifiers and ensemble schedules: C3S multi-system description.
Coverage and processing on this site
| Centre | Met Office, United Kingdom |
|---|---|
| System | GloSea6-GC5.1 (C3S system 610) |
| Forecast members used for probabilities | 50 latest qualifying members |
| Hindcast members used for probabilities | 28 per hindcast year |
| Reference period | 1993–2016 hindcast climatology |
| Published grid | C3S 1° global output; ±85° latitude shown. Native model grids differ. |
| Imported lead times | Lead months 1–6; four three-month windows. Some systems forecast further ahead. |
| Variables | 2 m temperature, precipitation, mean sea-level pressure, sea-surface temperature, 500 hPa geopotential height, 10 m wind speed and 850 hPa temperature |
| Products | Ensemble mean anomaly, tercile summary, median exceedance, tercile and outer-quintile probabilities |
| Source datasets | C3S monthly anomalies and monthly member statistics. Z500 and T850 use the corresponding pressure-level anomalies and pressure-level member statistics. |
These details describe the imported August and September 2026 runs. Each import resolves the system identifier for that initialization and checks it against the source metadata. Imports are run manually; a new monthly forecast may be available from the centre before it appears here. Check the initialization and system on the map panel.
Monthly ensemble-mean anomalies are supplied by C3S. Probabilities and three-month products are derived locally from operational C3S data; they are not synthetic sample forecasts. Member counts above describe the local probability calculation, not necessarily the full ensemble offered by a centre. See the C3S product definitions and the probability guide for reference and processing conventions.
UK Met Office against the other models
Each link opens UK Met Office next to one other centre for the same October 2026 initialization, with a shared valid period and scale. Differences can reflect model formulation, initialization, ensemble sampling and each system’s hindcast climate; they do not establish which model is more skilful.
- UK Met Office vs ECMWF SEAS5: January 2027 temperature
- UK Met Office vs Météo-France System 9: January 2027 temperature
- UK Met Office vs DWD GCFS 2.2: January 2027 temperature
- UK Met Office vs CMCC SPS4: January 2027 temperature
- ECMWF vs UK Met Office seasonal forecasts
- Europe seasonal temperature outlook: five models compared
- How the seasonal outlook changed between monthly runs