Koshu Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Koshu, Yamanashi, Japan. Long-term data from 1990 to 2020 was used to calculate these averages. Let's now guide you through the details for a complete overview.

Koshu has a notably wet climate with abundant precipitation, recording 1869 mm (74 in) of rain/snowfall per year. It does, however, have a distinct rainy season during certain months. Have a look at our detailed charts below to see how precipitation varies throughout the year.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

The seasons in Koshu, bring significant changes in precipitation. The wettest month, September, receives heavy rainfall, with an average of 240 mm (9.4 in) of precipitation. This rainfall is distributed across 19 rainy days.

In contrast, the driest month, December, experiences much less snow/rainfall, totaling 66 mm (2.6 in) over 10 snowy/rainy days. These distinct seasonal differences provide diverse experiences throughout the year.

September, the wettest month, has a maximum daytime temperature of 23°C (73°F). The city receives 152 hours of sunshine in this period. During the driest month December you can expect a temperature of 7°C (45°F). For more detailed insights into the city's temperatures, visit our Koshu Temperature page.

Koshu's average annual precipitation is 1869 mm (74 in). Let's compare this to some popular worldwide tourist destinations:

The city of Rome, Italy, has an average annual precipitation of 832 mm (33 in), spread fairly evenly throughout the year.

Osaka, Japan, experiences 1507 mm (59 in) of rainfall annually, spread across the year with wetter summers.

In Tokyo, Japan, the average annual precipitation is 1528 mm (60 in), with significant summer rains due to typhoon season.

Bangkok, Thailand, experiences a tropical monsoon climate with 1668 mm (66 in) of annual rainfall, with the heaviest precipitation occurring during September and October.

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

The proximity of a location to a large body of water can significantly affect its rainfall patterns:

• Ocean Influence: Coastal regions typically receive more rainfall due to the presence of moisture-laden winds from the ocean. These regions tend to have more humid climates and experience more frequent precipitation, especially in winter.
• Continental Climates: Areas further from the sea, such as inland or continental regions, experience less frequent rainfall and more extreme seasonal variations in precipitation.

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm (15 inches) wide and 20 cm (7.9 inches) thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA, over 31.5 meters (103 feet) fell during the winter of 1972.

For more detailed information about Koshu's weather, including sunshine hours, humidity levels, and temperature data, visit our Koshu Climate page.