Climate and monthly weather forecast
Kumamoto, Japan

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The climate of Kumamoto

Tucked away in the southern segment of Japan, Kumamoto is a city that experiences a Humid subtropical type of climate, known within the Köppen climate classification as Cfa. With no specific dry season, this climate classification sets the tone for Kumamoto's annual weather rhythm, providing a sense of predictability that is subject to mild alterations and variations.

A review of the climate data divulges a consistent pattern throughout the year. Temperature reaches the highest levels, peaking at 30.4°C (86.7°F) in August, and dropping to its lowest in January, with minimum temperatures recorded at 1.7°C (35.1°F). There is a smooth transition between these extremes, with the temperature gradually increasing in spring and early summer, and gradually declining in late autumn and winter.

Humidity too, mirrors a similar pattern. The average relative humidity hovers around 74-75% in colder months (from November to February), rises through the summer (reaching 83% in July), and then starts to decline in September.

Rainfall here follows a beautiful ebb and flow. The heaviest rainfall occurs in the monsoon months of June and July, with measures hitting the 200mm (7.87") mark, accompanied by rainfall days soaring up to 23. Precipitation decreases sharply to 105mm (4.13") in August and continues this downward trend until it hits its lowest mark in December, at 36mm (1.42").

The best time to visit Kumamoto

Given the trends in weather parameters, the period from April to June emerges as the most favorable time to visit Kumamoto. During these months, the average high temperature ranges from 18.3°C (64.9°F) in April to 25.2°C (77.4°F) in June, ensuring comfortable conditions for visitor activities. Relative humidity is on the lower side, fluctuating between 72 to 73%. Rainfall does start to creep up in May, but the average does not exceed 78mm (3.07"), and with daylight hours increasing from 13 to 14.3, travelers have ample opportunity to explore.

The worst time to visit Kumamoto

The least inviting months to visit Kumamoto are July and August. The hot and humid conditions, with temperatures rising to 30.4°C (86.7°F) and relative humidity scaling up to 83%, can be challenging. Moreover, the heavy rainfall during July of precipitation. Months with snowfall are January through March and December. January is the month with the most snowfall in Kumamoto. Snow falls for 3.3 days and accumulates 16mm (0.63") of snow. In January, the average sea temperature is 19°C (66.2°F).
Note: Most people find swimming in 19°C (66.2°F) to be not enjoyable. The control of one's breathing becomes more challenging as the water temperature drops below 21°C (69.8°F). In Kumamoto, the average length of the day in January is 10h and 16min.
On the first day of January in Kumamoto, Japan, sunrise is at 07:19 and sunset at 17:21. On the last day of the month, sunrise is at 07:13 and sunset at 17:47 JST. January has the least sunshine of the year, with an average of 5.1h of sunshine. The months with the lowest UV index are January and December, with an average maximum UV index of 2. A UV Index reading of 2, and below, represents a low threat to health from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum UV index of 2 during January leads to these instructions:
Many can withstand an hour in the sun without burning, yet children must always have protection against sunlight. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades. Be mindful! The reflection from snow can increase the Sun's UV radiation nearly twice.

Weather in February

The trend from cold to colder mildly fades away as February sees temperatures rising slightly in Kumamoto city. The highest ascent is recorded at 10.3°C (50.5°F) and the lowest descent hits at 3.1°C (37.6°F). Despite the increased temperature levels, umbrellas remain as needful as overcoats because February is rainier than January. Weather in February »

Weather in March

In March, the Kumamoto's weather conditions reveal spring's steady arrival, evident in a temperature hike up to 13.5°C (56.3°F) and a dive down to 5.6°C (42.1°F). Seasonal changes continue as the city sheds its winter coat and embraces warmer afternoons. Weather in March »

Weather in April

April in Kumamoto City observes an evident increase in thermal readings, ranging from a swell to 18.3°C (64.9°F) and a dip to 9.8°C (49.6°F), signifying the impending full bloom of spring. The city boasts comfortable balmy days and mildly nippy evenings. Weather in April »

Weather in May

May in Kumamoto experiences a considerable jump in temperature reaching a high of 23.2°C (73.8°F) and going down to 14.3°C (57.7°F). With summer knocking at the doorstep, the city feels the warmth in the air. More hours under the sun add to the prevailing warmth and while rain does arrive, it's minimal and fails to bring much cooling. Weather in May »

Weather in June

June in Kumamoto City ushers in summer, with temperatures hovering between a high of 25.2°C (77.4°F) and a low of 18.5°C (65.3°F). Coupled with these soaring temperatures, June sees a significant jump in rainfall. The city witnesses a climatic shift towards a 'hot and humid' character, aided by lengthy days under the sun. Weather in June »

Weather in July

In July, Kumamoto reaches its heated peak, as the summer temperature wavers between a maximum of 28.4°C (83.1°F) and a minimum of 22.3°C (72.1°F). As summer takes center stage, the city undergoes its warmest phase. Bright sunlight coupled with high humidity creates a distinct hot and muggy atmosphere. Weather in July »

Weather in August

August in Kumamoto city swelters under an intense summer heat with temperatures swinging from a high of 30.4°C (86.7°F) to a low of 23.3°C (73.9°F). The smouldering summer days dominate, making this month one of the hottest in the year. Weather in August »

Weather in September

As Kumamoto transitions into the fall, September records temperatures ranging from a maximum of 26.9°C (80.4°F) to a minimum of 19.6°C (67.3°F). With days gradually shortening, there is less daylight available, yet humidity levels remain moderately high. Weather in September »

Weather in October

October in Kumamoto ushers autumn into the fore with temperatures ranging from 22.5°C (72.5°F) to 15.1°C (59.2°F). The city sees a considerable reduction in warmth, making this an ideal time for outdoor sightseeing. The atmosphere remains comfortably dry with a decrease in the relative humidity level. Weather in October »

Weather in November

November in Kumamoto sees a sharp knockdown in temperature with figures swiveling between a high of 16.5°C (61.7°F) and a low of 9.9°C (49.8°F). The cool weather is an indicator of the impending winter season. The city enjoys mild and sunny days while the nights begin to see a crisp coolness. Weather in November »

Weather in December

As the year winds down, December brings winter to Kumamoto with a substantial dip in temperature, as the city alternates between a high of 10.4°C (50.7°F) and a low of 4.4°C (39.9°F). Along with a substantial drop in sea temperature, the colder weather is quite observable. Weather in December »

Frequently asked questions

What part of the year is the coldest in Kumamoto?

In Kumamoto, January is the month with the lowest recorded average temperatures, measuring a high of 8.3°C (46.9°F) and a low of 1.7°C (35.1°F).

What is the driest month in Kumamoto?

January is the month with the least rainfall. Rain falls for 10.5 days and accumulates 36mm (1.42") of precipitation.

How many days does it rain in Kumamoto?

In Kumamoto, Japan, during the entire year, the rain falls for 179.9 days and collects up to 1028mm (40.47") of precipitation.

When does it snow in Kumamoto?

January through March and December are months with snowfall.

When does it snow the most in Kumamoto?

January is the month with the most snowfall. Snow falls for 3.3 days and accumulates 16mm (0.63") of snow.

How much does it snow in Kumamoto?

Throughout the year, in Kumamoto, there are 7 snowfall days, and 38mm (1.5") of snow is accumulated.

What is the month with the least sunshine in Kumamoto?

The month with the least sunshine is January, with an average of 5.1h of sunshine.

When is the lowest UV index in Kumamoto?

January and December, with an average maximum UV index of 2, are months with the lowest UV index.

What are the months with the coldest sea water in Kumamoto?

February and March, with an average sea temperature of 18°C (64.4°F), are months with the coldest seawater.

What are the least humid months in Kumamoto?

March and April, with an average relative humidity of 72%, are the least humid months in Kumamoto.

When it does not snow in Kumamoto?

In Kumamoto, snow does not fall in April through November.

What is the rainiest month in Kumamoto?

The month with the most rainfall in Kumamoto, Japan, is June, when the rain falls for 20.8 days and typically aggregates up to 216mm (8.5") of precipitation.

When are the longest days in Kumamoto?

With an average of 14h and 18min of daylight, June has the longest days of the year.

What is the most humid month in Kumamoto?

With an average relative humidity of 83%, July is the most humid month in Kumamoto.

When is the highest UV index in Kumamoto?

July is the month with the highest UV index, with an average maximum UV index of 7.

What month is the hottest in Kumamoto?

August registers as the month with the average highest temperatures, reaching 30.4°C (86.7°F) at its peak and 23.3°C (73.9°F) at the lowest.

What is the month with the warmest sea water in Kumamoto?

The month with the warmest seawater in Kumamoto, Japan, is August, with an average sea temperature of 28°C (82.4°F).

What month has the most sunshine in Kumamoto?

August has the most sunshine of the year, with an average of 10.5h of sunshine.

What is the month with the shortest days in Kumamoto?

With an average of 10h and 0min of daylight, December has the shortest days of the year in Kumamoto.

Is there Daylight Saving Time (DST) in Kumamoto?

Kumamoto does not utilize Daylight Saving Time (DST). JST timezone is used over the entire year.

Average temperature
Kumamoto, Japan

Average temperature - Kumamoto, Japan

The warmest month (with the highest average high temperature) is August (30.4°C).
The month with the lowest average high temperature is January (8.3°C).

The month with the highest average low temperature is August (23.3°C).
The coldest month (with the lowest average low temperature) is January (1.7°C).

Average pressure
Kumamoto, Japan

Average pressure - Kumamoto, Japan

The month with the highest atmospheric pressure is January (1021.8mbar).
The month with the lowest atmospheric pressure is June (1008.2mbar).

Average wind speed
Kumamoto, Japan

Average wind speed - Kumamoto, Japan

The windiest month (with the highest average wind speed) is March (8.7km/h).
The calmest month (with the lowest average wind speed) is June (7km/h).

Average humidity
Kumamoto, Japan

Average humidity - Kumamoto, Japan

The month with the highest relative humidity is July (83%).
The months with the lowest relative humidity are March and April (72%).

Average rainfall
Kumamoto, Japan

Average rainfall - Kumamoto, Japan

The wettest month (with the highest rainfall) is June (216mm).
The driest month (with the least rainfall) is January (36mm).

Average rainfall days
Kumamoto, Japan

Average rainfall days - Kumamoto, Japan

The month with the highest number of rainy days is July (23.4 days).
The month with the least rainy days is January (10.5 days).

Average snowfall
Kumamoto, Japan

Average snowfall - Kumamoto, Japan

The month with the highest snowfall is January (16mm).
The months with the least snowfall are April, May, June, July, August, September, October and November (0mm).

Average snowfall days
Kumamoto, Japan

Average snowfall days - Kumamoto, Japan

The month with the highest number of snowfall days is January (3.3 days).
The months with the least snowfall days are April, May, June, July, August, September, October and November (0 days).

Average sea temperature
Kumamoto, Japan

Average sea temperature - Kumamoto, Japan

The best month for swimming (with the highest average sea temperature) is August (28°C).
The coldest months (with the lowest average sea temperature) are February and March (18°C).

Average daylight / Average sunshine
Kumamoto, Japan

Average daylight / Average sunshine - Kumamoto, Japan

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 5h and 6min).

Average sunshine days
Kumamoto, Japan

Average sunshine days - Kumamoto, Japan

The month with the most sunshine days is October (18.1 days).
The month with the least sunshine days is July (4.9 days).

Kumamoto, Japan

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