Responses and units

A successful request returns 200 with the profile. Everything is in SI units.

Levels

levels has one entry per requested height, sorted from lowest to highest.

Field	Unit	Description
altitude_agl_m	m	Height above the ground used for the request.
altitude_msl_m	m	Height above sea level.
wind_u_ms	m/s	Wind component towards the east.
wind_v_ms	m/s	Wind component towards the north.
wind_speed_ms	m/s	Horizontal wind speed.
wind_direction_deg	degrees	Direction the wind blows from, clockwise from true north.
temperature_k	K	Air temperature. Subtract 273.15 for °C.
pressure_pa	Pa	Air pressure. Divide by 100 for hPa.
specific_humidity_kg_kg	kg/kg	Mass of water vapour per mass of moist air.
relative_humidity_pct	%	Relative humidity over liquid water. Can exceed 100.
density_kg_m3	kg/m³	Density of moist air (water vapour included, cloud water excluded).

Wind direction

Wind direction follows the meteorological convention: a wind from the west is 270°, from the north 0°. With no wind at all the direction is reported as 0, which in that case doesn’t mean “from the north”.

Direction and speed are calculated from the interpolated u and v components, so they stay correct when the wind turns through north between two model levels.

The rest of the response

Field	Description
requested_time	The time you sent, in UTC.
valid_time	The model time step that was used.
latitude, longitude	The point you asked for.
altitude_reference	agl or msl, as requested.
ground_elevation_m_msl	The ground elevation used for agl heights.
model_ground_elevation_m_msl	The model’s terrain height at the grid point.
supplied_ground_elevation_m_msl	The ground elevation you sent, or null.
ground_source	caller if you supplied the ground elevation, otherwise model.
coverage	The lowest and highest heights available at this place and time.
provenance	Where the data came from (below).

Provenance

provenance records the model run and forecast hour, the grid point that was sampled (the nearest one on GFS’s 0.25° grid), when the data was downloaded, a SHA-256 hash of the source data, and the methods used for interpolation, heights, humidity and density. It also carries NOAA’s attribution and licence link. Keep it with the data if you store profiles.

All data is currently a forecast, so is_final is always false.

Caching

Responses include an X-Cache header: hit if the model data was already downloaded, miss if it was fetched for this request. Both count as a normal request; only a miss uses your daily data-fetch allowance.