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HOME > NWP Model Prediction > Probabilitic forecasts

One-month probabilistic forecasts at station points


18 september 2019
  • [Important prior notice] Please be advised that provision of One-month probabilistic forecasts at station points will be terminated by 24th March 2020.
    (For NMHS users; Please use "One-month guidance tool" instead of this guidance forecast information)

23 March 2017

28 April 2014
  • New forecast maps from 5 March to 9 April 2014 (initial forecast time) are currently available.

21 April 2014
  • Forecast maps from 5 March to 9 April 2014 (initial forecast time) are currently not available.
    New maps will be made available soon.

6 March 2014
  • JMA updated its one-month forecast system on 6 March 2014.

21 December 2012
  • Ensemble mean and standard deviation values have been newly added in the histogram for each forecast station point.
  • Forecast station (Hong Kong Observatory) has been newly added.


JMA started probabilistic one-month forecast for 7-day averaged surface temperature and 14-day averaged precipitation. The Model Output Statistics (MOS) technique with the 30-year (1981-2010) hindcasts is used to generate the forecasts. The thresholds of three categories (below normal, normal and above normal) are determined so that the climatological chance of occurrence for each category is 33.3% for the period from 1981 to 2010.
Model Outline is here.

Surface temperature
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