Climate - Hamamatsu (Japan)

In Hamamatsu, the climate is temperate, with quite mild, sunny winters and hot, humid and rainy summers. Like the rest of Japan, the city is affected by the monsoon circulation: in winter, the northwest cold currents prevail, while in summer, they are replaced by hot and humid currents of tropical origin.
Hamamatsu is located in the central part of the island of Honshu, on the coast, in the Shizuoka prefecture. North of the city lie the Kiso Mountains, or Central Alps, with a series of peaks almost 3,000 meters (9,800 ft) tall.
Given the relatively low latitude (on the 34th parallel) and the protection given by the mountains (we are on the southern side), in winter, the currents of Siberian origin are felt little, so there are many sunny days, and usually, it's not very cold. However, cold and windy periods, with highs around 6/8 °C (43/46 °F) or less, can not be ruled out. Snowfall is very rare: unlike in Tokyo, where it can sometimes snow, in practice it never snows (but sometimes, it can snow in the northern outskirts of the city, see Tenryu-ku). Night frosts are quite rare and usually light, however, at night, the temperature often drops near 0 °C (32 °F).
In summer, sunny and muggy periods alternate with periods of bad weather, with wind and rain. Fortunately, the breeze blows from the sea.
Here are the average temperatures.

In Hamamatsu, precipitation is abundant, in fact, it amounts to 1,800 millimeters (70 inches) per year. Winter is definitely the driest season. The rainiest periods are the first part of the rainy season (mid-June to mid-July, the plum rains) and the latest (September, also because of the contribution given by typhoons, see below). Here is the average precipitation.

From June to October (but especially from August to early October), Hamamatsu can be affected by typhoons, the tropical cyclones of the Pacific, which in this area, facing south, are felt in a particular way. The most intense typhoons can bring torrential rains and heavy damage.
The cherry blossoming in Hamamatsu takes place around the 30th of March.
The amount of sunshine in Hamamatsu is good in winter, while it is barely decent in the other seasons, due to weather disturbances in spring and autumn, as well as to the summer monsoon. In summer, August is the sunniest month: apart from typhoons and some waves of bad weather, there are several sunny periods. Here are the average sunshine hours per day.



The sea is warm enough for swimming, with a temperature of 23 °C (73 °F) or more, from July to October, as you can see in the following table.

Hamamatsu - Weather by month

Based on the period 1991-2020

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In January, the coldest month of the year, the weather in Hamamatsu is usually quite cold. The average temperature is of 6.1 °C (43 °F), with a minimum of 2.3 °C (36.1 °F) and a maximum of 10 °C (50 °F).
On the coldest nights of the month, the temperature usually drops to around -2 °C (28 °F). However, it dropped to -5 °C (23 °F) in January 1997.
On the warmest days of the month, the temperature usually reaches around 15 °C (59.5 °F). However, it reached 18 °C (64.4 °F) in January 1996.
Precipitation amounts to 60 mm (2.4 in), distributed over 6 days.
The day lasts on average 10 hours and 5 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 66% of the time.
The average humidity is 56%.
The average wind speed is 16 kph (10 mph).
The average sea temperature is of 18 °C (64 °F). Therefore, the sea is cold for swimming.

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In February, the weather in Hamamatsu is usually quite mild. The average temperature is of 6.9 °C (44 °F), with a minimum of 2.8 °C (37 °F) and a maximum of 11 °C (51.9 °F).
On the coldest nights of the month, the temperature usually drops to around -2 °C (28.5 °F). However, it dropped to -5 °C (23 °F) in February 1999.
On the warmest days of the month, the temperature usually reaches around 18 °C (64 °F). However, it reached 22 °C (71.6 °F) in February 2006.
Precipitation amounts to 75 mm (3 in), distributed over 6 days.
The day lasts on average 11 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 61% of the time.
The average humidity is 55%.
The average wind speed is 16 kph (10 mph).
The average sea temperature is of 17 °C (62.5 °F). Therefore, the sea is cold for swimming.

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In March, the weather in Hamamatsu is usually mild. The average temperature is of 10.1 °C (50 °F), with a minimum of 5.9 °C (42.6 °F) and a maximum of 14.4 °C (57.9 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 0 °C (32 °F). However, it dropped to -2 °C (28.4 °F) in March 2001.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 20.5 °C (68.5 °F). However, it reached 25 °C (77 °F) in March 2018.
Precipitation amounts to 145 mm (5.7 in), distributed over 10 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 54% of the time.
The average humidity is 58%.
The average wind speed is 15 kph (9 mph).
The average sea temperature is of 17.5 °C (63 °F). Therefore, the sea is cold for swimming.

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In April, the weather in Hamamatsu is usually very mild. The average temperature is of 14.9 °C (59 °F), with a minimum of 10.7 °C (51.2 °F) and a maximum of 19.1 °C (66.3 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 4 °C (39 °F). However, it dropped to 0 °C (32 °F) in April 1999.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 24.5 °C (76.5 °F). However, it reached 29 °C (84.2 °F) in April 2005.
Precipitation amounts to 180 mm (7.1 in), distributed over 10 days.
The day lasts on average 13 hours and 5 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 51% of the time.
The average humidity is 63%.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 18.5 °C (65.5 °F). Therefore, the sea is very cool for swimming.

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In May, the weather in Hamamatsu is usually warm. The average temperature is of 19.0 °C (66 °F), with a minimum of 15.1 °C (59.2 °F) and a maximum of 23 °C (73.3 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 10 °C (50.5 °F). However, it dropped to 7.8 °C (46 °F) in May 1991.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 28 °C (82.5 °F). However, it reached 31 °C (87.8 °F) in May 2015.
Precipitation amounts to 190 mm (7.5 in), distributed over 11 days.
The day lasts on average 14 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 70%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).
The average sea temperature is of 20.5 °C (69.5 °F). Therefore, the sea is cool for swimming.

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In June, the weather in Hamamatsu is usually warm. The average temperature is of 22.5 °C (73 °F), with a minimum of 19.4 °C (66.8 °F) and a maximum of 25.7 °C (78.3 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 15.5 °C (59.5 °F). However, it dropped to 13 °C (55.4 °F) in June 2010.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 31.5 °C (88.5 °F). However, it reached 36 °C (96.8 °F) in June 2011.
Precipitation amounts to 225 mm (8.9 in), distributed over 13 days.
The day lasts on average 14 hours and 25 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 5 hours of sunshine per day. So, the sun shines 34% of the time.
The average humidity is 79%. Hence, the air is normally humid.
The average wind speed is 12 kph (7 mph).
The average sea temperature is of 23 °C (74 °F). Therefore, the sea can be considered barely acceptable for swimming.

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In July, the weather in Hamamatsu is usually warm to hot and muggy. The average temperature is of 26.3 °C (79 °F), with a minimum of 23.2 °C (73.7 °F) and a maximum of 29.4 °C (84.8 °F).
On the coldest nights of the month, the temperature usually drops to around 19 °C (66.5 °F). However, it dropped to 16.8 °C (62.2 °F) in July 1992.
On the warmest days of the month, the temperature usually reaches around 34.5 °C (94 °F). However, it reached 37 °C (98.6 °F) in July 2001.
Precipitation amounts to 210 mm (8.3 in), distributed over 12 days.
The day lasts on average 14 hours and 10 minutes. So the days are long.
There are on average 5.5 hours of sunshine per day. So, the sun shines 40% of the time.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 26 °C (79 °F). Therefore, the sea is warm enough for swimming.

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In August, the hottest month of the year, the weather in Hamamatsu is usually very hot and muggy. The average temperature is of 27.6 °C (82 °F), with a minimum of 24.2 °C (75.6 °F) and a maximum of 30.9 °C (87.7 °F).
On the coldest nights of the month, the temperature usually drops to around 21 °C (69.5 °F). However, it dropped to 18.5 °C (65.3 °F) in August 1996.
On the warmest days of the month, the temperature usually reaches around 35.5 °C (96 °F). However, it reached 39 °C (102.2 °F) in August 2020.
Precipitation amounts to 125 mm (4.9 in), distributed over 8 days.
The day lasts on average 13 hours and 25 minutes.
There are on average 7 hours of sunshine per day. So, the sun shines 51% of the time.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is 12 kph (7 mph).
The average sea temperature is of 27.5 °C (82 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In September, the weather in Hamamatsu is usually warm to hot and muggy. The average temperature is of 24.5 °C (76 °F), with a minimum of 21.1 °C (70 °F) and a maximum of 27.9 °C (82.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 16 °C (60.5 °F). However, it dropped to 13 °C (55.4 °F) in September 1997.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 33 °C (91 °F). However, it reached 36 °C (96.8 °F) in September 1992.
Precipitation amounts to 245 mm (9.6 in), distributed over 12 days.
The day lasts on average 12 hours and 25 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 45% of the time.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 26.5 °C (80 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In October, the weather in Hamamatsu is usually warm. The average temperature is of 19.3 °C (67 °F), with a minimum of 15.6 °C (60.2 °F) and a maximum of 23 °C (73.3 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 10 °C (50 °F). However, it dropped to 6 °C (42.8 °F) in October 1997.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 28 °C (82.5 °F). However, it reached 31 °C (87.8 °F) in October 2013.
Precipitation amounts to 205 mm (8.1 in), distributed over 11 days.
The day lasts on average 11 hours and 20 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 46% of the time.
The average humidity is 71%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).
The average sea temperature is of 24 °C (75.5 °F). Therefore, the sea is warm enough for swimming.

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In November, the weather in Hamamatsu is usually mild. The average temperature is of 13.9 °C (57 °F), with a minimum of 10 °C (49.9 °F) and a maximum of 17.8 °C (64 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 4 °C (39.5 °F). However, it dropped to 2 °C (35.6 °F) in November 1995.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 23 °C (73 °F). However, it reached 26 °C (78.8 °F) in November 2000.
Precipitation amounts to 115 mm (4.5 in), distributed over 8 days.
The day lasts on average 10 hours and 20 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 55% of the time.
The average humidity is 65%.
The average wind speed is 12 kph (8 mph).
The average sea temperature is of 22 °C (71.5 °F). Therefore, the sea is cool for swimming.

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In December, the weather in Hamamatsu is usually quite mild. The average temperature is of 8.5 °C (47 °F), with a minimum of 4.6 °C (40.2 °F) and a maximum of 12.4 °C (54.4 °F).
On the coldest nights of the month, the temperature usually drops to around -0.5 °C (31.5 °F). However, it dropped to -3 °C (26.6 °F) in December 2012.
On the warmest days of the month, the temperature usually reaches around 18 °C (65 °F). However, it reached 23 °C (73.4 °F) in December 2015.
Precipitation amounts to 65 mm (2.6 in), distributed over 6 days.
The day lasts on average 9 hours and 55 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 6.5 hours of sunshine per day. So, the sun shines 65% of the time.
The average humidity is 60%.
The average wind speed is 15 kph (9 mph).
The average sea temperature is of 19.5 °C (67.5 °F). Therefore, the sea is very cool for swimming.