# Microsoft releases open-source tool to improve two‑to‑six‑week weather forecasts

> The new Probabilistic Bias Correction method can run on CPUs and boosts accuracy of existing models, helping farmers and emergency responders plan ahead.

Oossa · 2026-10-14 · https://oossa.com/en/microsoft-releases-open-source-tool-to-improve-two-to-six-week-weather-forecasts

Microsoft announced an open‑source machine‑learning tool that corrects systematic errors in existing weather models. The method, called Probabilistic Bias Correction (PBC), lets agencies produce more reliable forecasts two to six weeks out. It runs on ordinary CPUs, not on supercomputers or high‑end GPUs.

## How PBC improves forecasts

PBC learns the typical bias of a weather model—like a tendency to predict colder temperatures because the model was trained on older climate data—and adjusts the output. In tests, it raised the accuracy of the European Centre for Medium‑Range Weather Forecasts (ECMWF) physics‑based model for 98 % of precipitation targets and 92 % of temperature targets. It also doubled the accuracy of ECMF’s newer AI forecasting system.

## Why this matters

Because the software is lightweight and free, smaller weather services, especially in developing regions, can adopt it without costly hardware. Better medium‑range forecasts give farmers more time to protect crops and help emergency responders prepare for extreme weather events.

## The facts

- Microsoft published the research in Nature on 2026-10-14.
- The tool is open‑source and runs on CPUs.
- PBC improved ECMWF precipitation accuracy to 98 % and temperature accuracy to 92 %.
- It doubled the accuracy of ECMWF’s new AI forecasting system in the study.
- The work involved researchers from Microsoft, MIT, ECMWF and others.

## Why it matters

For everyday people, more accurate forecasts two to six weeks ahead can mean earlier warnings for storms or droughts, giving farmers and local officials a better chance to act. The low‑cost, open‑source nature of the tool means it could reach regions that previously lacked the computing power for advanced weather models.

## Sources & references

1. [Microsoft has a new machine learning tool to improve weather forecasts](https://www.theverge.com/science/1011127/ai-weather-forecast-microsoft) – The Verge, 2026-10-14

Last updated: 2026-10-14