Parses METAR raw data into structured data classes, capturing detailed weather information like temperature, wind, visibility, and cloud cover. Supports automated and manual observations.
Up to Kotlin 2.1.20 use
Since Kotlin 2.2.0 use
METARs typically come from airports or permanent weather observation stations. Reports are generated once an hour or half-hour at most stations, but if conditions change significantly at a staffed location, a report known as a special (SPECI) may be issued. There are stations that make regular reports more often.(Such as KPLU which reports 3 per hour.) Some METARs are encoded by automated airport weather stations located at airports, military bases, and other sites. Some locations still use augmented observations, which are recorded by digital sensors, encoded via software, and then reviewed by certified weather observers or forecasters prior to being transmitted. Observations may also be taken by trained observers or forecasters who manually observe and encode their observations prior to transmission.
A typical METAR contains data for the temperature, dew point, wind direction and speed, precipitation, cloud cover and heights, visibility, and barometric pressure. A METAR may also contain information on precipitation amounts, lightning, and other information that would be of interest to pilots or meteorologists such as a pilot report or PIREP, colour states and runway visual range (RVR). Read more.
This is an example for Ulyanovsk Central Airport METAR:
UWLL 251200Z 16008MPS 8000 -SN BLSN OVC013 M09/M13 Q1008 R20/820242 NOSIG RMK QFE746/0994
<dependency>
<groupId>io.github.alexmaryin.metarkt</groupId>
<artifactId>parser</artifactId>
<version>1.0.1</version>
</dependency>
implementation 'io.github.alexmaryin.metarkt:parser:1.0.1'
implementation("io.github.alexmaryin.metarkt:parser:1.0.1")
<dependency>
<groupId>io.github.alexmaryin.metarkt</groupId>
<artifactId>metarkt</artifactId>
<version>1.2.1</version>
</dependency>
implementation 'io.github.alexmaryin.metarkt:metarkt:1.2.1'
implementation("io.github.alexmaryin.parser:metarkt:1.2.1")
The main interface implemented in library is MetarParser. It's including companion object with
constructor of standard implementation: MetarParser.current().
Returning data type of Metar is composed of following values:
val station: String?,
val reportTime: LocalDateTime?,
val wind: Wind?,
val visibility: Visibility?,
Primitive properties:
station is parsed ICAO code of Airport or Weather observation station, i.e. UWLLreportTime report time in LocalDataTime format from kotlinx-datatime library.ceilingAndVisibilityOK return for statusphenomemons is the list of WeatherPhenomenon objects which contains:
group set of Phenomenons enum items (DRIZZLE, RAIN, SNOW, SNOW_GRAINS, ICE_PELLETS, SMALL_HAIL,
HAIL, SHOWER, FREEZE, THUNDERSTORM, DUST_STORM, SANDSTORM, FOG, IN_VICINITY, SHALLOW, PARTIAL, PATCHES,
MIST, HAZE, SMOKE, DUST, BLOWING, SQUALL, ICE_CRYSTALS, VOLCANIC_ASH, DRIFTING, SAND)clouds is the list of CloudLayer objects which contains:
air temperature of the air in CelsiusdewPoint temperature of the dew pointhPa sea level pressure in HectopascalsinHg sea level pressure in the Inch of mercuryHelper constructors:
PressureQNH.fromHpa(hPa: Int) - automatically adds converted inHg
PressureQNH.fromInHg(inHg: Float) - automatically adds converted hPa
PressureQNH.standard() - returns QNH (1013 hPa = 29.92 inHg)
mmHg ground level pressure in millimeters of mercuryhPa ground level pressure in HectopascalsHelper constructors:
PressureQFE(mmHg: Int) - automatically adds converted hPa
PressureQDE.standard() - returns QNE (760 mmHg = 1013 hPa)
val wind = Wind(direction = 225, speed = 10, speedUnits = WindUnit.KT)
val runway = 180 // true course not magnetic!
val component = wind.componentForRunwayTrue(runway)
Extension componentForRunwayTrue returns WindComponent object which contains:
data class WindComponent(
val headwind: Double, // positive = headwind, negative = tailwind
val crosswind: Double, // always positive magnitude
val fromLeft: Boolean // true if crosswind comes from the left
)
Convert QFE to QNH for ISA (Standard Atmosphere) as it using for METAR or ATIS reports:
val qfe = PressureQFE(mmHg = 750)
val elevation = 100 // meters
val actualQnh = qfe.toIsaQnh(elevation) // return 1011
Convert QFE to QNH for actual atmosphere concerning temperature:
val qfe = PressureQFE(mmHg = 750)
val elevation = 100 // meters
val temperature = 25 // celsius
val actualQnh = qfe.toCorrectedQnh(elevation, temperature) // return 1011
Apply FAA/ICAO cold-temperature correction to an indicated height above airport elevation:
val indicatedHeight = 1500 // feet above airport
val temperature = -20 // celsius
val correctedHeight = coldTemperatureCorrectedAltitude(indicatedHeight, temperature) // return 1710
The function interpolates correction values from the ICAO Cold Temperature Error Table and returns the corrected height in feet. The input height must be height above airport/reporting station elevation, not MSL altitude.
For instrument approaches, the FAA recommends applying corrections by segment (AIM 7-3-6). Use calculateColdTemperatureCorrections to get corrections for the intermediate and final segments:
val fafAltitude = 2000 // FAF published altitude (MSL)
val mdaAltitude = 1500 // MDA/DA published altitude (MSL)
airportElevation =
temperature = -
corrections = calculateColdTemperatureCorrections(
fafAltitude = fafAltitude,
mdaAltitude = mdaAltitude,
airportElevation = airportElevation,
reportedTemperatureC = temperature,
roundUpForSafety =
)
correctedFaf = corrections.correctIntermediateSegment(fafAltitude)
correctedMda = corrections.correctFinalSegment(mdaAltitude)
The ColdTemperatureCorrections object contains:
intermediateSegmentCorrection — correction to apply to all fixes in the intermediate segment (IAF through FAF)finalSegmentCorrection — correction to apply to MDA/DA and final segment stepdown fixesfafHeightAboveAirport — height of FAF above airport elevationmdaHeightAboveAirport — height of MDA above airport elevation (actual)The implementation follows the official FAA/ICAO rules for cold temperature altitude corrections:
For detailed guidance on applying cold temperature corrections during approaches, see CFI Notebook - Cold Temperature Operations.
Copyright 2021-2026 ALex Maryin
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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trueraw original METAR stringdirection value in degrees from which wind is blowingvariable is true if the direction is undefinedspeed average speed of the wind in original unitsspeedUnits units of the speed from enum WindUnit (KT, MPS, KPH)gusts max speed of the gustsisCalm return true if the wind is calmspeedKt, gustsKt - speed in KnotsspeedMps, gustsMps - speed in Meters per seconddistAll either visibility in defined units for the airfield or null if the visibility
defined by individual direction or runwaydistUnits units of visibility distance from enum VisibilityUnit (METERS, SM)byDirections list of VisibilityByDir objects which contains:
dist visibility in defined unitsdirection direction of this visibility distance from enum VisibilityDirection (NORTH, NORTH_EAST, EAST, SOUTH_EAST, SOUTH, SOUTH_WEST, WEST, NORTH_WEST)byRunways list of VisibilityByRunway objects which contains:
dist visibility in defined unitsrunway name of the runwayintensity flag of the intensity from enum PhenomenonIntensity (NONE, HIGH, LIGHT) for this grouptypeCloudsTypelowMarginFt low margin of the cloud layer in FeetcumulusType null if the clouds are not generating precipitation or one of the enum CumulusType type (CUMULONIMBUS, TOWERING_CUMULUS)mdaHeightAboveAirportRounded — height of MDA above airport elevation (rounded up for safety, if used)Surfaced from shared tags and platforms — no rankings paid for.