September weather forecastOtaru, Japan

September

Weather in September

September's weather characteristics in Otaru display a shift towards autumn, particularly with a decrease in average high temperatures. A welcome relief is the lowering of rainfall rates, with a decrease to 86mm (3.39") from the peak 119mm (4.69") witnessed in August. Changes in weather patterns resulting in fewer rain clouds, could provide more opportunities for outdoor activities. Despite the drop in temperature, sea temperatures remain relatively warm, remaining inviting for adventurous swimmers. Simultaneously, the daylight hours begin to dwindle, signalling the end of the extended summer days.

Temperature

The shift from August to September coincides with a small decrease in the average high-temperature, down to a refreshing 19.5°C (67.1°F) from a warm 23°C (73.4°F). Throughout September, Otaru registers a consistent average low-temperature of 13.2°C (55.8°F).

Humidity

The average relative humidity in September is 83%.

Rainfall

In Otaru, during September, the rain falls for 18.3 days and regularly aggregates up to 86mm (3.39") of precipitation. Throughout the year, in Otaru, there are 151.8 rainfall days, and 851mm (33.5") of precipitation is accumulated.

Snowfall

In Otaru, snow does not fall in June through September.

Sea temperature

In Otaru, the average seawater temperature in September is 20.6°C (69.1°F).
Note: For most, swimming in 20.6°C (69.1°F) is not a pleasant experience. As the temperature falls from 21°C (69.8°F) to 15°C (59°F), controlling one's breathing becomes more difficult.

Daylight

In Otaru, the average length of the day in September is 12h and 31min.
On the first day of the month, sunrise is at 05:00 and sunset at 18:11. On the last day of September, sunrise is at 05:32 and sunset at 17:19 JST.

Sunshine

The average sunshine in September is 7.7h.

UV index

In Otaru, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.
Note: In September, the maximum UV index of 4 suggests this advice:
Ensure safety - Sun damage prevention is strongly urged. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.

Updated: Jan 31, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

The average high-temperature, in September, in Otaru, is 19.5°C (67.1°F), while the average low-temperature is 13.2°C (55.8°F).

In September, the average relative humidity in Otaru, Japan, is 83%.

In Otaru, Japan, during September, the rain falls for 18.3 days and regularly aggregates up to 86mm (3.39") of precipitation.

June through September are months without snowfall in Otaru, Japan.

In Otaru, Japan, in September, it doesn't snow. In October, it regularly snows.

In Otaru, in September, the average water temperature is 20.6°C (69.1°F). For most, swimming in 20.6°C (69.1°F) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 21°C (69.8°F) to 15°C (59°F).

The average day length in September is 12h and 31min.

On the first day of September in Otaru, Japan, sunrise is at 05:00 and sunset at 18:11. On the last day of the month, sunrise is at 05:32 and sunset at 17:19 JST.

In Otaru, Japan, the average sunshine duration in September is 7.7h.

The average daily maximum UV index in September in Otaru is 4. A UV Index estimate of 3 to 5 represents a moderate vulnerability from exposure to Sun's UV rays.

Today

Tomorrow

Long-term

Year J F M A M J J A September O N D

Aug

September

Oct

Average high temperature

23°C

19.5°C

12.8°C

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

10.6km/h

12.4km/h

17.1km/h

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

Average snowfall

Average snowfall days

0.6

Average sea temperature

Average daylight

Average sunshine

Average sunshine days

9.9

9.2

11.5

Average UV index

Average cloud cover

Average visibility

Average temperature in September
Otaru, Japan

Average high temperature in September: 19.5°C

The warmest month (with the highest average high temperature) is August (23°C).
The month with the lowest average high temperature is January (-3.3°C).

Average low temperature in September: 13.2°C

The month with the highest average low temperature is August (16.8°C).
The coldest month (with the lowest average low temperature) is February (-8.2°C).

Average pressure in September
Otaru, Japan

Average pressure in September: 1013.4mbar

The month with the highest atmospheric pressure is November (1016.1mbar).
The month with the lowest atmospheric pressure is July (1008.5mbar).

Average wind speed in September
Otaru, Japan

Average wind speed in September: 11.9km/h

The windiest month (with the highest average wind speed) is December (19km/h).
The calmest month (with the lowest average wind speed) is July (9.2km/h).

Average humidity in September
Otaru, Japan

Average humidity in September: 83%

The month with the highest relative humidity is July (88%).
The months with the lowest relative humidity are April and October (79%).

Average rainfall in September
Otaru, Japan

Average rainfall in September: 86mm

The wettest month (with the highest rainfall) is August (119mm).
The driest month (with the least rainfall) is April (43mm).

Average rainfall days in September
Otaru, Japan

Average rainfall days in September: 18.3 days

The month with the highest number of rainy days is July (20.2 days).
The month with the least rainy days is February (2.5 days).

Average snowfall in September
Otaru, Japan

Average snowfall in September: 0mm

The month with the highest snowfall is January (369mm).
The months with the least snowfall are June, July, August and September (0mm).

Average snowfall days in September
Otaru, Japan

Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (26 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average sea temperature in September
Otaru, Japan

Average sea temperature in September: 20.6°C

The best month for swimming (with the highest average sea temperature) is August (21.6°C).
The coldest months (with the lowest average sea temperature) are February and March (5.3°C).

Average daylight in September /
Average sunshine in September
Otaru, Japan

Average daylight in September: 12h and 30min

The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).

Average sunshine in September: 7h and 42min

The months with the most sunshine are May and August (Average sunshine: 8h and 24min).
The month with the least sunshine is January (Average sunshine: 1h and 12min).

Average sunshine days in September
Otaru, Japan

Average sunshine days in September: 9.2 days

The month with the most sunshine days is May (14.8 days).
The month with the least sunshine days is January (3.1 days).

Average UV index in September
Otaru, Japan

Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, March, November and December (UV index 1).