GFS vs ECMWF Demand-Hub Outlook: 2026-04-14 00Z

Executive Summary

The 15-day outlook shows a material disagreement between models, with the ECMWF forecasting a significantly colder and more demand-supportive scenario than the GFS. This divergence is driven by a late-period cold shot in the high-demand Midwest and East hubs. Confidence in either specific outcome is low due to the model split, but both models have trended colder versus their prior runs, a key shift in the overall weather signal.

Hub-Level Weather

The primary drivers of the national forecast are the Midwest (Chicago, 35% weight) and East (New York City, 30% weight), where the models show their largest discrepancies.

• Midwest (Chicago): The ECMWF is substantially colder, projecting 190.8 cumulative HDDs versus the GFS's 153.6 HDDs. The divergence is most extreme late in the forecast period; on April 23-24, the ECMWF forecasts over 51 HDDs while the GFS sees virtually none.
• East (New York City): A similar and even more pronounced split exists, with the ECMWF forecasting 161.9 cumulative HDDs against only 104.1 HDDs from the GFS. This ~56 HDD difference is concentrated in the April 23-25 timeframe.
• South Central (Houston): In contrast, the GFS is warmer in the key cooling market, projecting 143.8 cumulative CDDs compared to the ECMWF's 111.7 CDDs. This highlights the GFS's warmer overall pattern in the southern U.S.

Demand Implications (Natural Gas)

The model differences translate directly to a split view on weather-driven natural gas demand, particularly for late-season heating.

• Heating Demand (HDDs): Nationally, the ECMWF forecasts 141.3 demand-weighted HDDs, which is 31% higher than the GFS's forecast of 107.4 weighted HDDs. The ECMWF outlook implies a stronger call on natural gas for residential/commercial heating than the GFS.
• Cooling Demand (CDDs): The GFS is modestly more constructive for cooling demand, forecasting 45.4 weighted CDDs versus 38.2 from the ECMWF. This is primarily driven by warmer forecasts in Houston and Atlanta.
• Run-over-Run Trends: The forecast has shifted colder since the last cycle. The GFS added 7.0 weighted HDDs, while the ECMWF made a more significant bullish change, adding 22.4 weighted HDDs. This collective colder trend is a notable development.

Model Agreement & Caveats

Forecast confidence is low due to significant model disagreement, particularly in the extended range (days 8-15).

• Divergence: The demand-weighted mean absolute HDD difference per day is 5.53, indicating a substantial and material split between the solutions. The convergence_score is 0.153.
• Caveats: The primary disagreement concerns the intensity and depth of a cold trough moving into the eastern two-thirds of the country late in the forecast period. The ECMWF is far more aggressive with this feature. Such long-range disagreements are common, and the market will likely await subsequent model runs for confirmation before fully pricing in either scenario.
• Source: This analysis is based on raw GFS and ECMWF model output from Open-Meteo and does not represent a final, blended forecast.