About ModelSpread

Weather forecasts should show what they do not know

ModelSpread is an independent weather-analysis project built to make forecast uncertainty understandable. Most weather products show one number. ModelSpread adds the range of plausible outcomes and the local track record behind that number.

What the site provides

• Official National Weather Service forecasts alongside calibrated NBM temperature and precipitation ranges.
• GFS and ECMWF ensemble guidance, showing how possible outcomes spread over time.
• Local historical temperature forecast errors by month and lead time.

Publisher and responsibility

ModelSpread is operated and published as an independent weather-data project. ModelSpread is responsible for the site’s calculations, explanations, corrections, and product decisions. It is not affiliated with NOAA, the National Weather Service, ECMWF, Open-Meteo, or ForecastWatch.

Data sources

Current official forecasts come from the National Weather Service. Model guidance includes NOAA’s National Blend of Models and ensemble data distributed through Open-Meteo. Historical observations and forecasts are processed using the methodology described on this site.

Publication standards

• Current forecasts and retrospective accuracy results are labeled separately.
• Raw model guidance is not presented as an official NWS forecast.
• Local pages identify their reporting station and its distance from the city ZIP center.
• Method changes, archive dates, limitations, and prospective-validation status are disclosed on the methodology page.

Corrections and contact

Reports of data errors, methodological concerns, and accessibility problems are reviewed through the contact page. Material corrections are reflected in the published dataset and methodology version.

Page last reviewed August 13, 2026.