stated on the page: nomads.ncep.noaa.gov

--- title: NOAA NOMADS (NCEP model output) summary: GFS, GEFS and other NCEP model output as GRIB2 over HTTPS, with a filter that cuts a region and variables. mount:

Open data and APIs

Left: what points at it. Right: what it points at. Each line carries its verb; a dashed line was not confirmed on the page cited, or the site does not say; the table below gives the page and the time read for each. From data-noaa-nomads.json

--- # NOAA NOMADS (NCEP model output) > Kept by incident.meteorology@web-summit.dinis, 11 November 2026, 11:36 UTC [Where a forecast comes from](../index.md) · Open data and APIs · id `data-noaa-nomads` · [as data](data-noaa-nomads.json) GFS, GEFS and other NCEP model output as GRIB2 over HTTPS, with a filter that cuts a region and variables. **Address:** [https://nomads.ncep.noaa.gov/](https://nomads.ncep.noaa.gov/) (leaves this site) ## What it is connected to, and who says so | This | Verb | That | The page that says so | Read | Check | |---|---|---|---|---|---| | NOAA NOMADS (NCEP model output) | **carries** | [GFS (NOAA/NCEP)](model-gfs.md) | [nomads.ncep.noaa.gov](https://nomads.ncep.noaa.gov/): "the column headings for description of each data access method. Data Set freq grib filter https Global Models AIGFS 6 hours - https AIGEFS 6 hours - https GDAS 6 hours grib filter https GDAS 0.25 6 hours grib filter http" | 11:29 UTC, 11 Nov | stated on the page | | NOAA NOMADS (NCEP model output) | **carries** | [GEFS (NOAA/NCEP)](model-gefs.md) | [nomads.ncep.noaa.gov](https://nomads.ncep.noaa.gov/): "description of each data access method. Data Set freq grib filter https Global Models AIGFS 6 hours - https AIGEFS 6 hours - https GDAS 6 hours grib filter https GDAS 0.25 6 hours grib filter https GFS 0.25 Degree 6 hour" | 11:29 UTC, 11 Nov | stated on the page | | NOAA NOMADS (NCEP model output) | **published by** | [NOAA (NWS, NCEP, NESDIS)](body-noaa.md) | [nomads.ncep.noaa.gov](https://nomads.ncep.noaa.gov/): "NOMADS at ncep.noaa.gov Home --> HOME Forecast Local Graphical Aviation Marine Rivers and Lakes Hurricanes Severe Weather Fire Weather Space Weather Sun/Moon Long Range Forecasts" | 11:29 UTC, 11 Nov | stated on the page | | NOAA NOMADS (NCEP model output) | **is what Open-Meteo takes its data from** | [Open-Meteo](data-open-meteo.md) | [open-meteo.com](https://open-meteo.com/en/licence): "Centre for Medium-Range Weather Forecasts ECMWF ( CC-BY Licence ) Atmospheric, ensemble and wave forecasts from NOAA NCEP ( Licence ) Atmospheric and ensemble forecasts from Canadian Meteorological Centre CMC ( Licence )" | 11:29 UTC, 11 Nov | stated on the page | ## Licence: what we may do with it **NOAA / US National Weather Service (GFS, NOMADS, Aviation Weather Center, NHC)**: US government work: public domain ([weather.gov](https://www.weather.gov/disclaimer), read 11:30 UTC, 11 Nov, stated on the page). | Read | Store | Show | Transform | Attribution | |---|---|---|---|---| | yes | yes | yes | yes | Not required; NOAA asks not to claim it as your own and not to imply endorsement. We credit "NOAA/NWS". | Do not present modified data as official NWS information. ## What it offers for Lisbon and Madeira this week GFS at 0.25°, hourly to 120 h: the filter cuts a box and chosen variables on the server, so the gust field for the Lisbon to Madeira box is a file of under 2 KB. - **Endpoint:** `https://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_0p25.pl` - **Key:** none - **Format:** GRIB2 - **Size:** a full file is 477 to 513 MB per time step; our cut-out (surface gust, 32 to 40 N, 18 to 8 W, one step) was 1,702 bytes - **Cadence:** four runs a day (00, 06, 12, 18 UTC), on the server about 3.5 to 5 hours after run time (18 UTC run: first file 21:34 UTC) - **This week** (probe read 02:29 UTC, 11 Nov): Read 02:29 UTC: the 18 UTC run of 10 November was there; directories from 1 to 10 November. Public domain: the one global model we may transform with no condition at all. - **How to read it:** `filter_gfs_0p25.pl?dir=/gfs.YYYYMMDD/HH/atmos&file=gfs.tHHz.pgrb2.0p25.fNNN&var_GUST=on&lev_surface=on&subregion=&toplat=40&leftlon=-18&rightlon=-8&bottomlat=32` - **Limits:** Ten days of runs are kept. Binary: decode outside git. NOAA asks for no more than 120 hits a minute. --- Not a warning service: this page explains where data comes from. For warnings follow [IPMA](https://www.ipma.pt/pt/otempo/prev-sam/) and ANEPC.