Climate - Okinawa (Japan)

The climate of Okinawa is sub-tropical, with very mild winters and long, muggy and rainy summers.
Okinawa is an archipelago, which includes the main island of the same name plus some smaller islands (Kumejima, Agunijima, Iejima etc.). In the nearby archipelagos of Kerama, Daito, and Iheya, the climate is similar.
Here are the average temperatures in the capital, Naha.

Although the winter is very mild, the sky is often cloudy, and periods of bad weather, with wind and rain, are quite common. Sometimes, especially in January and February, there may be very cool or slightly cold days, with maximum temperatures around 15 °C (59 °F) or below, and minimum temperatures around 10 °C (50 °F) or below.
In January 2016, there was a day with a minimum of 6 °C (43 °F) and a maximum of 10 °C (50 °F).
The long summer is muggy, with fairly frequent and sometimes abundant rains. The first part of the rainy season, called plum rains (Baiu), arrives one month earlier than on the main islands of Japan, so it occurs in May and June: not only the rains are frequent, but also the sun is seen quite rarely.
Here are the average daily sunshine hours.

The rains are abundant, especially in the hot period. In July, there is a relative pause, in fact, the rains decrease and sunshine becomes pretty frequent (although this does not happen every year, for example, in the year 2015, June has been quite dry, while July has been very rainy). In the second part of summer (August, September and early October), the rains increase again, but the amount of sunshine is generally decent, and certainly better than in May and June.
Here is the average precipitation.

From June to October, with a maximum from August to early October, Okinawa can be affected by typhoons, the tropical cyclones of Southeast Asia. Of the 26 typhoons that form on average every year in the northwestern Pacific, 3 or 4 pass close enough to Okinawa to threaten it or at least to have an impact on the weather. On September 22, 1999, the island was hit by Super Typhoon Bart, which unloaded 700 millimeters (27.5 inches) of rain in two days, and caused severe damage due to high winds.



The sea in Okinawa is never cold, in fact, the temperature drops to a minimum of 22 °C (72 °F) in February, while it becomes very warm in summer. Here are the average sea temperatures.

The cherry blossoming in Okinawa occurs as early as in winter, and is longer than on the main islands of Japan: two or three weeks pass from the beginning to full flowering (which occurs on average around February 1st).

Okinawa - Weather by month

Based on the period 1991-2020

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In January, the coldest month of the year, the weather in Okinawa is usually very mild. The average temperature is of 17.4 °C (63 °F), with a minimum of 14.9 °C (58.8 °F) and a maximum of 19.8 °C (67.6 °F).
On the coldest nights of the month, the temperature usually drops to around 10.5 °C (51 °F). However, it dropped to 6.1 °C (43 °F) in January 2016.
On the warmest days of the month, the temperature usually reaches around 24.5 °C (76 °F). However, it reached 27 °C (80.6 °F) in January 2020.
Precipitation amounts to 100 mm (3.9 in), distributed over 12 days.
The day lasts on average 10 hours and 40 minutes.
There are on average 3 hours of sunshine per day. So, the sun shines 28% of the time.
The average humidity is 66%.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 22.5 °C (72.5 °F). Therefore, the sea can be considered barely acceptable for swimming.

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In February, the weather in Okinawa is usually very mild. The average temperature is of 17.6 °C (64 °F), with a minimum of 15.1 °C (59.2 °F) and a maximum of 20.2 °C (68.4 °F).
On the coldest nights of the month, the temperature usually drops to around 11 °C (52 °F). However, it dropped to 8.5 °C (47.3 °F) in February 1996.
On the warmest days of the month, the temperature usually reaches around 25 °C (77 °F). However, it reached 26.7 °C (80.1 °F) in February 2020.
Precipitation amounts to 115 mm (4.5 in), distributed over 11 days.
The day lasts on average 11 hours and 20 minutes.
There are on average 3.5 hours of sunshine per day. So, the sun shines 29% of the time.
The average humidity is 69%.
The average wind speed is 15 kph (9 mph).
The average sea temperature is of 22 °C (71.5 °F). Therefore, the sea is cool for swimming.

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In March, the weather in Okinawa is usually warm. The average temperature is of 19.3 °C (67 °F), with a minimum of 16.7 °C (62.1 °F) and a maximum of 21.9 °C (71.4 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 12 °C (54 °F). However, it dropped to 9 °C (48.2 °F) in March 2005.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 26.5 °C (79.5 °F). However, it reached 28.2 °C (82.8 °F) in March 1999.
Precipitation amounts to 145 mm (5.7 in), distributed over 13 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 3.5 hours of sunshine per day. So, the sun shines 31% of the time.
The average humidity is 71%. Hence, the air is normally humid.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 22.5 °C (72 °F). Therefore, the sea can be considered barely acceptable for swimming.

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In April, the weather in Okinawa is usually warm. The average temperature is of 21.7 °C (71 °F), with a minimum of 19.1 °C (66.4 °F) and a maximum of 24.3 °C (75.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 14.5 °C (58 °F). However, it dropped to 12.5 °C (54.5 °F) in April 1993.
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 29.2 °C (84.6 °F) in April 2001.
Precipitation amounts to 160 mm (6.3 in), distributed over 12 days.
The day lasts on average 12 hours and 50 minutes.
There are on average 4 hours of sunshine per day. So, the sun shines 31% of the time.
The average humidity is 75%. Hence, the air is normally humid.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 23.5 °C (74.5 °F). Therefore, the sea can be considered barely acceptable for swimming.

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In May, the weather in Okinawa is usually warm to hot and muggy. The average temperature is of 24.6 °C (76 °F), with a minimum of 22.1 °C (71.8 °F) and a maximum of 27 °C (80.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 18 °C (64.5 °F). However, it dropped to 16.2 °C (61.2 °F) in May 1991.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 30 °C (86 °F). However, it reached 31.8 °C (89.2 °F) in May 2019.
Precipitation amounts to 245 mm (9.6 in), distributed over 13 days.
The day lasts on average 13 hours and 25 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 33% of the time.
The average humidity is 78%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).
The average sea temperature is of 25 °C (77.5 °F). Therefore, the sea is warm enough for swimming.

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In June, the weather in Okinawa is usually warm to hot and muggy. The average temperature is of 27.5 °C (82 °F), with a minimum of 25.2 °C (77.4 °F) and a maximum of 29.8 °C (85.6 °F).
On the coldest nights, the temperature usually drops to around 21.5 °C (71 °F). However, it dropped to 19.2 °C (66.6 °F) in June 1993.
On the warmest days, the temperature usually reaches around 32.5 °C (90.5 °F). However, it reached 34.1 °C (93.4 °F) in June 2001.
Precipitation amounts to 285 mm (11.2 in), distributed over 12 days.
The day lasts on average 13 hours and 50 minutes. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 5.5 hours of sunshine per day. So, the sun shines 38% of the time.
The average humidity is 83%. Hence, the air is normally humid.
The average wind speed is 15 kph (9 mph).
The average sea temperature is of 27 °C (81 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In July, the hottest month of the year, the weather in Okinawa is usually very hot and muggy. The average temperature is of 29.4 °C (85 °F), with a minimum of 27 °C (80.6 °F) and a maximum of 31.9 °C (89.4 °F).
On the coldest nights of the month, the temperature usually drops to around 24.5 °C (76 °F). However, it dropped to 21 °C (69.8 °F) in July 2009.
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F). However, it reached 35.1 °C (95.2 °F) in July 2017.
Precipitation amounts to 190 mm (7.5 in), distributed over 11 days.
The day lasts on average 13 hours and 35 minutes.
There are on average 7.5 hours of sunshine per day. So, the sun shines 54% of the time.
The average humidity is 78%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).
The average sea temperature is of 29 °C (84 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In August, the weather in Okinawa is usually very hot and muggy. The average temperature is of 29.3 °C (85 °F), with a minimum of 26.8 °C (80.2 °F) and a maximum of 31.8 °C (89.2 °F).
On the coldest nights of the month, the temperature usually drops to around 24.5 °C (76.5 °F). However, it dropped to 22.1 °C (71.8 °F) in August 2000.
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F). However, it reached 35.6 °C (96.1 °F) in August 2001.
Precipitation amounts to 240 mm (9.4 in), distributed over 14 days.
The day lasts on average 13 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 51% of the time.
The average humidity is 78%. Hence, the air is normally humid.
The average wind speed is 16 kph (10 mph).
The average sea temperature is of 29 °C (84.5 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In September, the weather in Okinawa is usually very hot and muggy. The average temperature is of 28.2 °C (83 °F), with a minimum of 25.8 °C (78.4 °F) and a maximum of 30.6 °C (87.1 °F).
On the coldest nights, the temperature usually drops to around 23 °C (74 °F). However, it dropped to 19.5 °C (67.1 °F) in September 1997.
On the warmest days, the temperature usually reaches around 33 °C (91 °F). However, it reached 34.6 °C (94.3 °F) in September 2009.
Precipitation amounts to 275 mm (10.8 in), distributed over 13 days.
The day lasts on average 12 hours and 20 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 49% of the time.
The average humidity is 75%. Hence, the air is normally humid.
The average wind speed is 12 kph (7 mph).
The average sea temperature is of 28.5 °C (83.5 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In October, the weather in Okinawa is usually warm to hot and muggy. The average temperature is of 25.8 °C (78 °F), with a minimum of 23.5 °C (74.3 °F) and a maximum of 28.1 °C (82.6 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 20 °C (68 °F). However, it dropped to 17.9 °C (64.2 °F) in October 1991.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 31 °C (88 °F). However, it reached 33 °C (91.4 °F) in October 2017.
Precipitation amounts to 180 mm (7.1 in), distributed over 11 days.
The day lasts on average 11 hours and 30 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 46% of the time.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 27 °C (81 °F). Therefore, the sea is pleasantly warm and allows long swims.

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In November, the weather in Okinawa is usually warm to hot. The average temperature is of 22.7 °C (73 °F), with a minimum of 20.4 °C (68.7 °F) and a maximum of 25 °C (77 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 16.5 °C (61.5 °F). However, it dropped to 12.9 °C (55.2 °F) in November 1995.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 28.5 °C (83.5 °F). However, it reached 30.8 °C (87.4 °F) in November 2008.
Precipitation amounts to 120 mm (4.7 in), distributed over 10 days.
The day lasts on average 10 hours and 55 minutes.
There are on average 4 hours of sunshine per day. So, the sun shines 37% of the time.
The average humidity is 69%.
The average wind speed is 16 kph (10 mph).
The average sea temperature is of 25.5 °C (78 °F). Therefore, the sea is warm enough for swimming.

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In December, the weather in Okinawa is usually warm. The average temperature is of 19.2 °C (66 °F), with a minimum of 16.8 °C (62.2 °F) and a maximum of 21.5 °C (70.7 °F).
On the coldest nights of the month, the temperature usually drops to around 12.5 °C (55 °F). However, it dropped to 10 °C (50 °F) in December 2005.
On the warmest days of the month, the temperature usually reaches around 26 °C (79 °F). However, it reached 29.4 °C (84.9 °F) in December 2018.
Precipitation amounts to 110 mm (4.3 in), distributed over 11 days.
The day lasts on average 10 hours and 30 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 3.5 hours of sunshine per day. So, the sun shines 33% of the time.
The average humidity is 67%.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 24 °C (75 °F). Therefore, the sea is warm enough for swimming.