The AI Weather Quest Testing Period is now officially open. Running from mid-May to mid-August 2025, it gives registered participants a chance to test their models and the submission of forecasts, and to self-evaluate results ahead of the Competition Phase, which starts in August.
Forecasts submitted during the Testing Period will not be ranked, allowing teams to experiment and improve freely.
What is the AI Weather Quest?
The AI Weather Quest, organised by ECMWF under the Destination Earth initiative and supported by the World Meteorological Organization (WMO), is an international competition advancing the use of artificial intelligence (AI) and machine learning (ML) in sub-seasonal weather forecasting.
Participants are challenged to generate global probabilistic forecasts for three key variables:
- near-surface (2 m) temperature
- mean sea level pressure
- precipitation.
Forecasts must cover two specific lead time windows:
- days 19–25 after forecast initialisation
- days 26–32 after forecast initialisation.
Submissions must provide quintile probabilities at a 1.5° global resolution.
What participants can do during the Testing Period
During this phase, participants can:
- submit forecasts using the official AI Weather Quest Python package
- self-evaluate forecasts using the provided evaluation tools
- check submission status and compare their results to dynamical models via the AI Weather Quest Forum
- experiment without pressure – forecasts will not be publicly ranked.
The Testing Period offers participants the perfect opportunity to finalise technical workflows and build confidence before the Competition Phase begins.
Resources available to participants
ECMWF provides several resources to support participants:
- the AI-WQ-package, a Python toolkit for forecast submission and evaluation
- Testing Period launch webinar videos, including a demo on how to submit and self-evaluate: Resources • AI Weather Quest
- an interactive AI Weather Quest Forum to stay updated and connect with the community.
Why engage now?
Participating in the Testing Period helps teams to
- refine their AI/ML models and submission workflows
- understand the evaluation method
- address technical issues early
- connect with the AI Weather Quest community and ECMWF organisers.
Prepare for the Competition Phase
The Competition Phase of the AI Weather Quest will begin in August 2025 and run until at least September 2026. During this phase, teams will submit weekly, real-time forecasts and benchmark their models against operational standards.
To help participants get ready, ECMWF is hosting two Pre-Competition Webinars on 22 July 2025:
These webinars will provide final guidelines, show how to visualise forecasts, and explain how results will be displayed during the competition.
Join the Quest
Teams registered by 1 August 2025 will be eligible to join the Competition Phase from the start and compete across the full year cycle.
Not yet registered? Register now at aiweatherquest.ecmwf.int.