In 2023, the annual average rainfall in Japan amounted to around **** thousand millimeters. Figures increased compared to about **** thousand millimeters in the previous year. Most of the rain fell during the rainy season, which is the time of year when most of a region's average annual rainfall occurs. Seasonal rainfall In most of Japan, the rainy season lasts from early June to mid-July. In the southernmost prefecture Okinawa, it roughly starts a month earlier, while the northernmost main island Hokkaido is less affected. Heavy rainfall can cause floods, which can lead to landslides and mudflows in mountainous areas. In recent years, flooded houses accounted for the highest number of damage situations in natural disasters. Furthermore, heavy rain and floods are often caused by typhoons, which develop over the Pacific Ocean and regularly approach the archipelago between July and October. Since the number of typhoons has increased in recent years, the amount of damage caused by floods grew as well. Climate change Climate change has affected Japan in recent years, resulting in increased rainfall and an increase of the average annual temperature in Tokyo. These weather changes can intensify natural disasters such as heavy rain and typhoons. In recent years, Japan was among the countries with the most natural disasters. To counter global warming, Japan aims to reduce greenhouse gas emissions by increasing its renewable and nuclear energy share.

Precipitation in Japan increased to 1791.61 mm in 2024 from 1640.03 mm in 2023. This dataset includes a chart with historical data for Japan Average Precipitation.

In 2024, the precipitation in the Japanese capital Tokyo was highest in August, reaching *** millimeters. December and January represented the months with the lowest rainfall.

The precipitation in Kyoto, Japan amounted to around *** thousand millimeters in 2024. Figures peaked in 2015, reaching approximately **** thousand millimeters of rainfall. In 2024, June was by far the month with the highest precipitation.

This dataset contains dekadal rainfall indicators, computed from Climate Hazards Group InfraRed Precipitation satellite imagery with insitu Station data (CHIRPS) version 2 and the CHIRPS-GEFS short term rainfall forecasts, aggregated by subnational administrative units.

Included indicators are (for each dekad):

• 10 day rainfall mm
• rainfall 1-month rolling aggregation mm
• rainfall 3-month rolling aggregation mm
• rainfall long term average mm
• rainfall 1-month rolling aggregation long term average mm
• rainfall 3-month rolling aggregation long term average mm
• rainfall anomaly %
• rainfall 1-month anomaly %
• rainfall 3-month anomaly %

The administrative units used for aggregation are based on WFP data and contain a Pcode reference attributed to each unit. The number of input pixels used to create the aggregates, is provided in the n_pixels column. Finally, the type column indicates if the value is based on a forecast, a preliminary or a final product.

Forecasts are issued on the 6th, 16th, and 26th of each month for the upcoming 10-day period (dekad), then updated with improved versions on the 1st, 11th, and 21st. Preliminary observations replace the previous dekad’s forecast on the 3rd, 13th, and 23rd, and are later replaced by final observations—published mid-month (13th or 23rd)—covering all three dekads of the prior month. Please find a summary below:

Publication Day: Forecast type, Covers (Dekad)

• 1st: Updated forecast, 1–10 of the same month
• 6th: Initial forecast, 11–20 of the same month
• 11th: Updated forecast, 1–10 of the same month
• 16th: Initial forecast, 21–end of the same month
• 21st: Updated forecast, 11–20 of the same month
• 26th: Initial forecast, 1–10 of the following month

For more on CHIRPS-GEFS forecasts, see: https://www.chc.ucsb.edu/data/chirps-gefs

For further details, please see the methodology section.

Japan: Precipitation, mm per year: The latest value from 2021 is 1668 mm per year, unchanged from 1668 mm per year in 2020. In comparison, the world average is 1168 mm per year, based on data from 178 countries. Historically, the average for Japan from 1961 to 2021 is 1668 mm per year. The minimum value, 1668 mm per year, was reached in 1961 while the maximum of 1668 mm per year was recorded in 1961.

Japan Maximum 5-day Rainfall: 25-year Return Level data was reported at 16.534 mm in 2050. Japan Maximum 5-day Rainfall: 25-year Return Level data is updated yearly, averaging 16.534 mm from Dec 2050 (Median) to 2050, with 1 observations. The data reached an all-time high of 16.534 mm in 2050 and a record low of 16.534 mm in 2050. Japan Maximum 5-day Rainfall: 25-year Return Level data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Japan – Table JP.World Bank.WDI: Environmental: Climate Risk. A 25-year return level of the 5-day cumulative precipitation is the maximum precipitation sum over any 5-day period that can be expected once in an average 25-year period.;World Bank, Climate Change Knowledge Portal (https://climateknowledgeportal.worldbank.org);;

Japan JP: Average Precipitation in Depth data was reported at 1,668.000 mm/Year in 2014. This stayed constant from the previous number of 1,668.000 mm/Year for 2012. Japan JP: Average Precipitation in Depth data is updated yearly, averaging 1,668.000 mm/Year from Dec 1962 (Median) to 2014, with 12 observations. The data reached an all-time high of 1,668.000 mm/Year in 2014 and a record low of 1,668.000 mm/Year in 2014. Japan JP: Average Precipitation in Depth data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Japan – Table JP.World Bank.WDI: Land Use, Protected Areas and National Wealth. Average precipitation is the long-term average in depth (over space and time) of annual precipitation in the country. Precipitation is defined as any kind of water that falls from clouds as a liquid or a solid.; ; Food and Agriculture Organization, electronic files and web site.; ;

With over * thousand millimeters, the weather observing station in Miyazaki, Japan, measured the highest annual precipitation in 2023. In contrast, there were only about *** millimeters of rainfall in Nagano.

In 2024, the precipitation in Osaka amounted to around **** thousand millimeters. The decade-highest precipitation was recorded in 2021, with over two thousand millimeters.

In 2024, the annual precipitation in Sapporo, the capital of the northernmost Japanese island Hokkaido, reached 1120 millimeters. The figure reached a decade-low in 2019, with only *** millimeters.

GCOM-W/AMSR2 L3 Precipitation (1-Day,0.1 deg) dataset is obtained from the AMSR2 sensor onboard GCOM-W and produced by the Japan Aerospace Exploration Agency (JAXA). GCOM-W was launched by the H-IIA Launch Vehicle No. 21 (H-IIA F21) at 1:39 a.m. on May 18th, 2012 (Japan Standard Time, JST) and inserted into a planned position on the "A-Train" orbit. GCOM-W equipped with AMSR2 takes measurements at multiple microwave frequencies and multiple polarizations of weak electromagnetic waves in the microwave band radiated from the Earth’s surface and the atmosphere. AMSR2 has swath of 1450 km and 7 microwave bands. The observation data will enable the creation of long-term trustworthy data sets of global physical amount. The Level 3 process uses as its inputs one day's worth of Level 1B data and Level 2 data and calculates, by taking a simple arithmetic mean, the daily statistical mean value at each grid point in the specified mapping projection method (either equi-rectangular or polar stereo). Furthermore, Level 3 processing takes one month's worth of each geophysical parameter's Level 3 daily statistical mean values and calculates the monthly statistical mean value at each grid point using a simple arithmetic mean in the same way as the daily statistical mean calculation. The statistical means are calculated separately for observations along the satellite's ascending and descending tracks. This dataset includes Precipitation (PRC) overwritten by latest data. Although "precipitation" is usually defined as amount of water, which reaches the surface of the earth from atmosphere as rain and/or snow, microwave imager's precipitation products provide amount of rain (surface rainfall). Coverage of the product is global, and unit is [mm/h]. Accuracy of rainfall estimate over land, however tends to be lower than that over the ocean. Method of rainfall estimate used in AMSR2 precipitation product is also applied to "Global Rainfall Watch" system, which distributes global rainfall map in near-real-time. Missing value is -32768. When there is no geophysical data within observation swath, this value is set up when computing neither the case where the amount of geophysics is incomputable, nor the amount of geophysics. Error values are -32761 to -32767. It is outside observation swath data. The provided format is HDF5. The Sampling resolution is 0.1degree grid. The statistical period is 1 day. The current version of the product is Version 2. The Version 1 is also available. The projection method is EQR. The generation unit is global.

In 2024, the average air temperature in Japan's capital reached around **** degrees Celsius. Tokyo's annual mean air temperature increased by **** degrees Celsius since 1900, showing the progress of global warming. Weather in Tokyo Tokyo lies in the humid subtropical climate zone. It is affected by the monsoon circulation and has mild, sunny winters and hot, humid, and rainy summers. In most of Japan, the rainy season lasts from early June to mid-July. Furthermore, heavy rainfall is often caused by typhoons, which develop over the Pacific Ocean and regularly approach the archipelago between July and October. In recent years, the Kanto region, including Tokyo Prefecture, was approached by at least two typhoons each year. Since the winters are rather mild in Tokyo, the capital city does not often see snowfall and the snow rarely remains on the ground for more than a few days. Effects of global warming in Japan The increasing air temperature is one of the main consequences of global warming. Other effects are increased flooding frequency and a rise in sea levels due to melting ice caps. Global warming has already influenced Japan's climate in recent years, resulting in more frequent heat waves as well as increased annual rainfall. These weather changes can intensify natural disasters such as typhoons and inhibit the growth of crops. To counter global warming, Japan aims to reduce its greenhouse gas emissions by increasing its renewable and nuclear energy share.

Data used in figures and tables in the manuscript.Data1. Data of catchment location, catchment area, elevation, mean slope, geology, vegetation, and observed annual precipitation, annual runoff and annual mean temperature and calculated evapotranspiration and Inter-catchment groundwater flow in 152 forested catchments in Japan. The observed annual precipitation, annual runoff, temperature, and site information data were collected from published articles or reports. We used grid precipitation and temperature data from 1 km2 mesh grid data [The Agro-Meteorological Grid Square Data, National Agriculture and Food Research Organization (https://amu.rd.naro.go.jp/)].Data 2. Annual mean precipitation (P) and temperature (T) for 1986-1990 at 66 meteorological stations in Japan and potential evapotranspiration (E0), evapotranspiration (ET) estimated by Kondo et al (1992) and this study.Data 3. Annual water balance and mean temperature data in Shirasaka Experimental Watershed, Ananomiya Experimental Watershed, Higashiyama Experimental Watershed, Kiryu Experimental Watershed catchment K, M, A, Kamabuchi Experimental Watershed catchment No1, No2, and Sarukawa Experimental Watershed.Data 4. Surface watershed area, ratio of bedrock watershed area, IGF and ECI data of Fudoji Experimental Watershed.

TRMM/PR L3 Monthly Rainfall is obtained from the PR sensor onboard TRMM and produced by the Japan Aerospace Exploration Agency (JAXA). The Precipitation Radar (PR) is the primary instrument onboard TRMM. The most innovative of the five TRMM instruments, the PR is the first quantitative rain radar instrument to be flown in space. The major objectives of the PR instrument are as follows:a. Provides a 3-dimensional rainfall structureb. Achieves quantitative measurements of the rain rates over both land and ocean When properly combined with TMI measurements, the Precipitation Radar (PR) data is instrumental in obtaining the height profile of the precipitation content, from which the profile of latent heat release from the Earth can be estimated. The rain rate is estimated from the radar reflectivity factor when the rain rate is small by applying conventional algorithms used for ground-based radar. For large rain rates, a rain attenuation correction is made using the total-path attenuation of land or sea surface echoes.Monthly average of rain parameter at the height of 2, 4, 6, (10, 15) km in lon./lat. 5deg x 5deg and 0.5deg x 0.5deg region using TRMM/PR 1C21, 2A21, 2A23 and 2A25. (* 10,15km data are available only for 5deg x 5deg gridded region.The provided format is HDF4. The statistical period is 1 month. The current version of the product is Version 7. The generation unit is global.

In 2024, the annual precipitation in Tokyo amounted to over 1.93 thousand millimeters. The figure peaked in 2021 at over two thousand millimeters.

In 2024, the precipitation in Miyazaki, Japan amounted to almost three thousand millimeters. Miyazaki is the capital city of Miyazaki prefecture, which is located on the southern main island Kyushu.

In 2020, the total amount of damage cost caused by floods in Japan amounted to over *** billion Japanese yen. This was a large decrease compared to around two trillion Japanese yen in the previous year. From late June through mid-July, there were floods and mudflows due to severe rainfall.

Seasonal rainfall and floods in Japan

In most of Japan, the rainy season lasts from early June to mid-July. Heavy rainfall can cause floods, which in turn can lead to landslides and mudflows in mountainous areas. Flooded houses accounted for the highest number of damage situations in natural disasters. Furthermore, heavy rainfall and floods are often caused by typhoons, which develop over the Pacific Ocean and regularly approach the archipelago between July and October. Japanese people stated wind gusts and tornadoes as well as flooding as their leading fears regarding typhoons.

Climate change in Japan

Climate change has influenced Japan in recent years, resulting in increased average annual rainfall and an increase in the average annual temperature in Tokyo. These changes are already affecting the flora and fauna in Japan: The growth of crops such as rice plants is often inhibited as the weather is no longer suitable for their cultivation. Corals in the Japanese sea started to die due to rising sea temperatures, and tiger mosquitoes are now found further north. Furthermore, these weather changes can intensify natural disasters such as heavy rainfall and typhoons. To counter global warming, Japan aims to reduce greenhouse gas emissions by increasing its renewable and nuclear energy share.

Meteorological statistics of municipalities between 2007 and 2020 in four regional groups.

description: The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan satellite mission to monitor tropical and subtropical precipitation and to estimate its associated latent heating. TRMM was successfully launched on November 27, at 4:27 PM (EST) from the Tanegashima Space Center in Japan. The precipitation-relevant instruments on the TRMM satellite include the Precipitation Radar (PR), an electronically scanning radar operating at 13.8 GHz; TRMM Microwave Image (TMI), a nine-channel passive microwave radiometer; and Visible and Infrared Scanner (VIRS), a five-channel visible/infrared radiometer. The purpose of the 3B42 algorithm is to produce TRMM- and raingauge-adjusted multi-satellite precipitation rate (in mm/hr) and root-mean-square (RMS) precipitation-error estimates. The algorithm combines multiple independent precipitation estimates from the TMI, Advanced Microwave Scanning Radiometer for Earth Observing Systems (AMSR-E), Special Sensor Microwave Imager (SSMI), Special Sensor Microwave Imager/Sounder (SSMIS), Advanced Microwave Sounding Unit (AMSU), Microwave Humidity Sounder (MHS), and microwave-adjusted merged geo-infrared (IR). All input microwave data are intercalibrated to TRMM Combined Instrument (TCI) precipitation estimates (TRMM product 3B31); the IR estimates are computed using monthly matched microwave-IR histogram matching; then missing data in individual 3-hourly merged-microwave fields are filled with the IR estimates. After the preprocessing is complete, the 3-hourly multi-satellite fields are summed for the month and combined with the monthly accumulated Global Precipitation Climatology Centre (GPCC) rain gauge analysis using inverse-error-variance weighting to form a monthly best-estimate precipitation rate, which is TRMM Product 3B43. The final step is to scale all the 3-hourly estimates for the month to sum to the monthly value (for each gridbox separately). The final 3B42 precipitation (in mm/hr) estimates have a 3-hourly temporal resolution and a 0.25x0.25 spatial resolution. The spatial coverage is the latitude band 50S to 50N. Important Changes: After the initial Version 7 processing, it was discovered that AMSU data were neglected in the first retrospective processing of both the Version 7 TMPA (3B42/43) and TMPA-RT (3B40/41/42RT) data series, which created an important shortcoming in the inventory of microwave precipitation estimates used during 2000-2010. In addition, a coding error in the TMPA-RT replaced the occasional missings in product 3B42RT with zeros. Accordingly, both product series were retrospectively processed again. The main impact in both series was to improve the fine-scale patterns of precipitation during 2000-2010 (and for 3B4xRT into late 2012). Averages over progressively larger time/space scales should be progressively less affected. [This is the reason the lack of AMSU went undiscovered; the merger system copes very reasonably with missing data.] Nonetheless, users are urged to switch to the newest Version 7 data sets. The newest runs may be identified by the file names: V.7 3B42/43 suffix of "7A.HDF" for January 2000 - September 2010 V.7 3B4xRT suffix of "7R2.bin" for 1 March 2000 - 6 November 2012 It continues to be the case that the Version 7 3B42/43 is some 4% higher than the calibrating data set (2B31) over oceans, which is still under study. However, the initial conclusion is that it results from the sampling mismatch between the (very sparse) TCI and the (much denser) microwave constellation. At the large scales this offset seems to be nearly a proportional constant. TMPA Restarted with October 2014: On October 07, 2014, routine production ended for the TRMM PR precipitation estimates. Since PR is no longer available, the TMI/PR combined instrument (TCI) estimates are also no longer available. As products 3B42/3B43 use the TCI estimates as the satellite calibrator, September 2014 is the last month these products were produced in this way. In a...; abstract: The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan satellite mission to monitor tropical and subtropical precipitation and to estimate its associated latent heating. TRMM was successfully launched on November 27, at 4:27 PM (EST) from the Tanegashima Space Center in Japan. The precipitation-relevant instruments on the TRMM satellite include the Precipitation Radar (PR), an electronically scanning radar operating at 13.8 GHz; TRMM Microwave Image (TMI), a nine-channel passive microwave radiometer; and Visible and Infrared Scanner (VIRS), a five-channel visible/infrared radiometer. The purpose of the 3B42 algorithm is to produce TRMM- and raingauge-adjusted multi-satellite precipitation rate (in mm/hr) and root-mean-square (RMS) precipitation-error estimates. The algorithm combines multiple independent precipitation estimates from the TMI, Advanced Microwave Scanning Radiometer for Earth Observing Systems (AMSR-E), Special Sensor Microwave Imager (SSMI), Special Sensor Microwave Imager/Sounder (SSMIS), Advanced Microwave Sounding Unit (AMSU), Microwave Humidity Sounder (MHS), and microwave-adjusted merged geo-infrared (IR). All input microwave data are intercalibrated to TRMM Combined Instrument (TCI) precipitation estimates (TRMM product 3B31); the IR estimates are computed using monthly matched microwave-IR histogram matching; then missing data in individual 3-hourly merged-microwave fields are filled with the IR estimates. After the preprocessing is complete, the 3-hourly multi-satellite fields are summed for the month and combined with the monthly accumulated Global Precipitation Climatology Centre (GPCC) rain gauge analysis using inverse-error-variance weighting to form a monthly best-estimate precipitation rate, which is TRMM Product 3B43. The final step is to scale all the 3-hourly estimates for the month to sum to the monthly value (for each gridbox separately). The final 3B42 precipitation (in mm/hr) estimates have a 3-hourly temporal resolution and a 0.25x0.25 spatial resolution. The spatial coverage is the latitude band 50S to 50N. Important Changes: After the initial Version 7 processing, it was discovered that AMSU data were neglected in the first retrospective processing of both the Version 7 TMPA (3B42/43) and TMPA-RT (3B40/41/42RT) data series, which created an important shortcoming in the inventory of microwave precipitation estimates used during 2000-2010. In addition, a coding error in the TMPA-RT replaced the occasional missings in product 3B42RT with zeros. Accordingly, both product series were retrospectively processed again. The main impact in both series was to improve the fine-scale patterns of precipitation during 2000-2010 (and for 3B4xRT into late 2012). Averages over progressively larger time/space scales should be progressively less affected. [This is the reason the lack of AMSU went undiscovered; the merger system copes very reasonably with missing data.] Nonetheless, users are urged to switch to the newest Version 7 data sets. The newest runs may be identified by the file names: V.7 3B42/43 suffix of "7A.HDF" for January 2000 - September 2010 V.7 3B4xRT suffix of "7R2.bin" for 1 March 2000 - 6 November 2012 It continues to be the case that the Version 7 3B42/43 is some 4% higher than the calibrating data set (2B31) over oceans, which is still under study. However, the initial conclusion is that it results from the sampling mismatch between the (very sparse) TCI and the (much denser) microwave constellation. At the large scales this offset seems to be nearly a proportional constant. TMPA Restarted with October 2014: On October 07, 2014, routine production ended for the TRMM PR precipitation estimates. Since PR is no longer available, the TMI/PR combined instrument (TCI) estimates are also no longer available. As products 3B42/3B43 use the TCI estimates as the satellite calibrator, September 2014 is the last month these products were produced in this way. In a...