The Automated Meteorological Data Acquisition System (AMeDAS) is a collection of Automatic Weather Stations (AWSs) run by JMA for automatic observation of precipitation, wind direction/speed, temperature and humidity to support real-time monitoring of weather conditions with high temporal and spatial resolution. AMeDAS data play an important role in mitigating the risk of weather-related disasters.

  JMA began operating the AMeDAS system, which currently includes as many as 1,300 rain gauges at average intervals of 17 km nationwide, on 1st November 1974. Around 840 stations also observe wind direction/speed, temperature and humidity in addition to precipitation, and snow depth is observed at about 330 manned and unmanned stations in snowy districts.

List of Observation Sites

(PDF)
• List of observation sites (in Japanese) [PDF]

(CSV)
• List of observation sites (in Japanese) [ZIP compressed]
• List of observation sites (snow) (in Japanese) [ZIP compressed]

Display of AMeDAS data on the JMA website

Latest weather

Observation element	Description	Unit
Precipitation amount	Amount of rainfall or snowfall	Expressed in units of 0.5 mm. Snow, hailstone and graupel amounts are given as melted-water equivalents.
Wind direction	Direction of wind origin	Expressed using 16 compass points (north (N), north-northeast (NNE), northeast (NE), east-northeast (ENE), east (E), east-southeast (ESE), southeast (SE), south-southeast (SSE), south (S), south-southwest (SSW), southwest (SW), west-southwest (WSW), west (W), west-northwest (WNW), northwest (NW) and north-northwest (NNW)) based on the average for the 10-minute period before the observation time. By way of example, “northeast” represents wind blowing from the northeast.
Wind speed	Velocity of wind	Expressed in units of 0.1 m/s (1 m/s on maps) based on the average for the 10-minute period before the observation time.
Temperature	Air temperature	Expressed in units of 0.1 degrees Celsius.
Sunshine duration*	Number of hours of sunshine	Expressed in units of 0.1 hours (6 minutes). By way of example, an hour of sunshine (e.g., from 11:00 to 12:00) is expressed as 1 hour.
Snow depth	Height of snow surface from the ground	Expressed in units of 1 cm.
Humidity	Air relative humidity	Expressed as a percentage

Examples of AMeDAS Data on the JMA Website

Name	Time	Temperature	Precipitation amount	Wind direction and speed	Sunshine duration*	Snow depth	Humidity
Map
Table

*Sunshine durations are estimated from meteorological satellite observation on unmanned stations (other than Special Automated Weather Stations). The element is displayed as “Sunshine duration (estimate)”.