Weather Calendar (Latest version)

Weather calendars are shown here, using observational data by the Japan Meteorological Agency (JMA). Firstly, "fine day", "cloudy day" and "precipitation day" are defined as follows:

• Fine day = A day without precipitation equal to or more than 1 mm, and with cloud amount smaller than 8.5/10.
• Cloudy day = A day without precipitation equal to or more than 1 mm, and with cloud amount equal to or greater than 8.5/10.
• Precipitation day = A day with precipitation equal to or more than 1 mm.

Further, a precipitation day with a daily mean temperature equal to or higher than 2 deg. C is classified into a "rainy day", and that with a temperature lower then 2 deg. C a "snowy day". Then, we examine which of the three types like fine days, cloudy days and precipitation days appears most often on a day of the year. If fine days are the most often the case, the day of the year is regarded as "fine", and if cloudy days are, it is regarded as "cloudy". If precipitation days are most often the case, we compare the frequencies of rainy days and snowy days with each other. If rainy days are the more often the case, the day is classified into "rain", and if snowy days are, it is classified into "snow". The period for the statistics is a 59-year period from 1961 to 2019. Data shown here are no more than statistical results. Please remember that they are not a weather forecast.

Data at selected sites: | Sapporo | Sendai | Niigata | Tokyo | Osaka | Fukuoka | Naha | Marcus I. (24N,154E) |
Locations of the sites

Supplement: Detailed data: | Sapporo | Sendai | Niigata | Tokyo | Osaka | Fukuoka | Naha | Marcus I. (24N,154E) |
Format: DDD MM DD W(1:Fair,2:Cloudy,3:Rain,4:Snow) R(Fair) R(Cloudy) R(Rain/snow)