The Rapid Refresh Forecast System (RRFS) is NOAA's next-generation, hourly updated, convection-allowing weather model, built on the Finite-Volume Cubed-Sphere (FV3) dynamical core used by most of NOAA's global models. As of October 2026 it is scheduled to become operational on 10/14/26, together with an ensemble that NOAA calls the RRFS Ensemble Forecast System, or REFS.
What it covers
Version 1 of the RRFS runs on a 3-km grid across North America, with 2.5-km output for Hawaii and Puerto Rico and a separate 1.5-km fire weather run. Like the High-Resolution Rapid Refresh (HRRR), it focuses on the next one to three days.
A new run starts every hour and goes out 18 hours. The 00, 06, 12 and 18 UTC runs go out 84 hours.
The REFS ensemble
REFS runs five RRFS ensemble members out to 60 hours at 00, 06, 12 and 18 UTC. For the contiguous United States and Alaska, the HRRR adds two more members, from the current run and the run 6 hours earlier, and REFS also includes several time-lagged members, forecasts started at earlier times.
What it replaces
NOAA says RRFS and REFS will replace the North American Mesoscale model (NAM), the High Resolution Ensemble Forecast (HREF), the Short-Range Ensemble Forecast (SREF) and the High-Resolution Window (HiresW) runs. Those systems are scheduled to retire on 10/14/26.
In June 2026, NOAA said the HRRR and the Rapid Refresh (RAP) are not being retired at this time. NOAA expects the HRRR to be retired with a later RRFS upgrade that changes the atmospheric dynamical core.
A moving schedule
The first notice, in May 2026, set implementation for 08/31/26. A July update moved it to 10/06/26, and a September update moved it to 10/14/26.
NOAA says further changes will be announced through Service Change Notices. Like any convection-allowing model, the RRFS can still misplace or mistime individual storms, so read it alongside other guidance.