Climate Insights for Koga

Onga-gun, Fukuoka Prefecture, Japan

Hottest
August
31°C peak
Coldest
February
6°C low
Wettest
July
284mm rain
Best to Visit
Varies throughout year

Climate Overview

The climate in Koga is temperate. The average annual temperature is 17°C and approximately 1721mm of precipitation falls per year. Koga receives a notable amount of rainfall throughout the year, including during its driest month. Koga is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, September. The coldest months are February, January, December, when temperatures can drop to 6°C. Light snow can occur between January and February.

Temperature

10° 20° 30° 40° Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Max: 10° Average: 8° Min: 6° Feb Max: 10° Average: 8° Min: 6° Mar Max: 14° Average: 11° Min: 9° Apr Max: 18° Average: 15° Min: 13° May Max: 22° Average: 20° Min: 17° Jun Max: 25° Average: 23° Min: 21° Jul Max: 28° Average: 26° Min: 25° Aug Max: 31° Average: 28° Min: 26° Sep Max: 27° Average: 25° Min: 23° Oct Max: 22° Average: 20° Min: 18° Nov Max: 17° Average: 15° Min: 13° Dec Max: 12° Average: 10° Min: 8°
Max
Average
Min

Temperatures in Koga vary considerably across the year, with a 25°C difference between the coldest and warmest months. The warmest month is August, when average highs reach 31°C and the mean temperature sits around 28°C. February is the coolest month, with minimum temperatures around 6°C and an average of 8°C. Daily temperature variation is modest, with an average difference of 4°C between highs and lows. The sharpest temperature change occurs between October and November, with a 5°C shift in average temperatures.

Precipitation

0mm 50mm 100mm 150mm 200mm 250mm 300mm Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Precipitation: 96mm Snow: 6mm Feb Precipitation: 80mm Snow: 3mm Mar Precipitation: 132mm Snow: 0mm Apr Precipitation: 150mm Snow: 0mm May Precipitation: 125mm Snow: 0mm Jun Precipitation: 225mm Snow: 0mm Jul Precipitation: 284mm Snow: 0mm Aug Precipitation: 141mm Snow: 0mm Sep Precipitation: 220mm Snow: 0mm Oct Precipitation: 126mm Snow: 0mm Nov Precipitation: 52mm Snow: 0mm Dec Precipitation: 91mm Snow: 1mm
Precipitation
Snow

Koga is a fairly wet location, receiving approximately 1721mm of precipitation annually, which averages out to around 143mm per month. The wettest month is July, averaging 284mm of rainfall. June and September also tend to see above-average precipitation. The driest month is November, with just 52mm. That's 232mm less than July, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Light snowfall can occur between January and February, totalling around 9cm annually. January is the snowiest month with approximately 6cm.

Wind

0km/h 5km/h Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Wind Speed: 5km/h Feb Wind Speed: 5km/h Mar Wind Speed: 5km/h Apr Wind Speed: 4km/h May Wind Speed: 4km/h Jun Wind Speed: 4km/h Jul Wind Speed: 4km/h Aug Wind Speed: 4km/h Sep Wind Speed: 4km/h Oct Wind Speed: 5km/h Nov Wind Speed: 4km/h Dec Wind Speed: 5km/h
Wind Speed

Koga is relatively calm, with an average annual wind speed of 4km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is January, averaging 5km/h, though still comfortable for most outdoor activities. The calmest conditions occur in June, with average winds dropping to 4km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 1km/h between the calmest and windiest months.

Seasons

Winter
Dec 21
Spring
Mar 20
Summer
Jun 21
Autumn
Sep 23

3 days until Summer

It is currently spring in Koga, which began on March 20, 2026. Koga is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in August at around 31°C, while the coldest stretch bottoms out in February near 6°C. Summer is next, beginning on June 21, 2026 — 3 days from now.

Spring

Temperatures range from 9 to 22°C. Rainfall is heavy, totalling around 407mm across the season with a monthly average of 136mm. Winds are generally light, averaging 4km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.

Summer

Temperatures range from 21 to 31°C. Rainfall is heavy, totalling around 650mm across the season with a monthly average of 217mm. Winds are generally light, averaging 4km/h. Light, breathable clothing is ideal — perfect conditions for outdoor activities.

Autumn

Temperatures range from 13 to 27°C. Rainfall is heavy, totalling around 397mm across the season with a monthly average of 132mm. Winds are generally light, averaging 4km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.

Winter

Temperatures range from 6 to 12°C. Precipitation is moderate at around 267mm for the season, averaging 89mm per month. Expect around 9cm of snow accumulation during this period. Winds are generally light, averaging 5km/h. A light jacket or sweater is usually sufficient, though cooler evenings may call for an extra layer.

Monthly Climate Data

The table below shows monthly climate averages for Koga based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.

Month
Min Temperature
Max Temperature
Wind Speed
Precipitation
Snow
Jan
6 °C
10 °C
5 km/h
96 mm
6 cm
Feb
6 °C
10 °C
5 km/h
80 mm
3 cm
Mar
9 °C
14 °C
5 km/h
132 mm
0 cm
Apr
13 °C
18 °C
4 km/h
150 mm
0 cm
May
17 °C
22 °C
4 km/h
125 mm
0 cm
Jun Current
21 °C
25 °C
4 km/h
225 mm
0 cm
Jul
25 °C
28 °C
4 km/h
284 mm
0 cm
Aug
26 °C
31 °C
4 km/h
141 mm
0 cm
Sep
23 °C
27 °C
4 km/h
220 mm
0 cm
Oct
18 °C
22 °C
5 km/h
126 mm
0 cm
Nov
13 °C
17 °C
4 km/h
52 mm
0 cm
Dec
8 °C
12 °C
5 km/h
91 mm
1 cm
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