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Weather in Karuizawa for September 2025

Your guide to Karuizawa weather in September - trends and predictions

    Temperatures

  • Until now, September 2025 in Karuizawa has been nearly identical to the historical average, with a temperature of 23.8 °C (showing only a slight deviation of -0.2 °C).

  • The forecast for the next days in Karuizawa predicts a temperature of 19.9 °C, which is cooler than the historical average.

  • In general, the average temperature in Karuizawa at the beginning of September is 24.6 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 18.9 °C by the end of September.

    • Rain 🌧️

  • Karuizawa experiences heavy rainfall in September, with over 20 rainy days and an average total precipitation 129.9 mm.

    • More

  • Is September a good time to visit Karuizawa? check out the best time to travel to Karuizawa page.

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
6
Dry days
Average rainy days
24
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/14°
Temperatures
Average wind speed
8 km/h
Avg max wind
Average humidity
86 %
Avg humidity

Karuizawa Weather September

Move between months or click on a day
August
October
Mon.Tue.Wed.Thu.Fri.Sat.Sun.
1
Patchy rain possible
27°
2
Patchy rain possible
28°
3
Light rain shower
23°
4
Patchy rain possible
20°
5
Light rain shower
22°
6
Patchy rain possible
24°
7
Patchy rain possible
28°
8
Light rain shower
25°
9
Light rain shower
25°
10
Light rain shower
23°
11
Light rain shower
22°
12
Light rain shower
21°
13
Light rain shower
25°
14
Heavy rain
25°
15
Moderate rain
24°
16
Patchy rain possible
26°
17
Patchy rain possible
28°
18
Moderate rain
24°
19
Patchy rain possible
15°
20
Moderate rain
11°
21
Patchy rain possible
13°
22
Patchy rain possible
16°
23
Patchy rain possible
16°
24
Moderate rain
15°
25
Patchy rain possible
19°
26
Patchy rain possible
24°
27
Patchy rain possible
22°
28
Light rain shower
20°
29
Light rain shower
16°
30
Fog
16°

Temperatures trend during September in Karuizawa

See the weather trend as well as the moving average line

September weather in Karuizawa day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Patchy rain possible
Patchy rain possible
 27° /18° 1.1 mm 6
2 Sept. Patchy rain possible
Patchy rain possible
 28° /17° 2.6 mm 7
3 Sept. Light rain shower
Light rain shower
 23° /16° 11.2 mm 5
4 Sept. Patchy rain possible
Patchy rain possible
 20° /13° 3.7 mm 5
5 Sept. Light rain shower
Light rain shower
 22° /14° 29 mm 5
6 Sept. Patchy rain possible
Patchy rain possible
 24° /13° 0.1 mm 6
7 Sept. Patchy rain possible
Patchy rain possible
 28° /14° 1.7 mm 6
8 Sept. Light rain shower
Light rain shower
 25° /17° 13.3 mm 6
9 Sept. Light rain shower
Light rain shower
 25° /17° 5.8 mm 6
10 Sept. Light rain shower
Light rain shower
 23° /15° 7.7 mm 5
11 Sept. Light rain shower
Light rain shower
 22° /15° 10.1 mm 5
12 Sept. Light rain shower
Light rain shower
 21° /15° 8.9 mm 5
13 Sept. Light rain shower
Light rain shower
 25° /16° 12.7 mm 6
14 Sept. Heavy rain
Heavy rain
 25° /18° 25 mm 1.6
15 Sept. Moderate rain
Moderate rain
 24° /17° 8.6 mm 1.4
16 Sept. Patchy rain possible
Patchy rain possible
 26° /16° 4.3 mm 1.9
17 Sept. Patchy rain possible
Patchy rain possible
 28° /16° 3.1 mm 1.8
18 Sept. Moderate rain
Moderate rain
 24° /15° 9.1 mm 1
19 Sept. Patchy rain possible
Patchy rain possible
 15° /11° 0.5 mm 3
20 Sept. Moderate rain
Moderate rain
 11° /11° 10.5 mm 3
21 Sept. Patchy rain possible
Patchy rain possible
 13° /11° 1.2 mm 3
22 Sept. Patchy rain possible
Patchy rain possible
 16° /9° 0.1 mm 3
23 Sept. Patchy rain possible
Patchy rain possible
 16° /10° 4.2 mm 3
24 Sept. Moderate rain
Moderate rain
 15° /11° 8.7 mm 3
25 Sept. Patchy rain possible
Patchy rain possible
 19° /13° 4.9 mm 4
26 Sept. Patchy rain possible
Patchy rain possible
 24° /13° 1.9 mm 4
27 Sept. Patchy rain possible
Patchy rain possible
 22° /14° 0.7 mm 4
28 Sept. Light rain shower
Light rain shower
 20° /13° 4.8 mm 5
29 Sept. Light rain shower
Light rain shower
 16° /13° 2.3 mm 4
30 Sept. Fog
Fog
 16° /12° 0.6 mm 4
Next
Important Notice
Our weather forecast for Karuizawa in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Karuizawa forecast closer to your planned date for the most up-to-date weather information.
Change Month
‹
›

Karuizawa weather in September vs August vs October

Compare September weather in Karuizawa with the previous and following months. See how temperature, rainfall, wind, and other conditions change throughout the year to help you plan your visit.
AugustSeptemberOctober
WeatherPatchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Temperatures25°/17°22°/14°17°/9°
Rainfall286 mm130 mm176 mm
Wind7.1 km/h8.1 km/h8.6 km/h
Humidity86%86%86%
Rainy days26 days24 days13 days
Dry days5 days6 days18 days

Planning a trip to Karuizawa? Discover the best time to visit

Karuizawa in September - FAQ

What are the expected maximum and minimum temperatures in Karuizawa during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 14°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Karuizawa during September?
Significant rainfall exceeding 129.9 mm is expected in Karuizawa during September, occurring over more than 24 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Karuizawa during September?
The average wind speed in Karuizawa during September is 8 km/h, suggesting breezy to windy conditions, depending on your activities.

What to pack to Karuizawa in September?

As you prepare for your trip to Karuizawa in September, it's important to consider the typical weather patterns for the time of year. Below is a carefully tailored packing list to ensure that your time in Karuizawa, during September, is comfortable and enjoyable, regardless of the weather conditions.

  • Clothing
    • Warm Clothing: Sweaters, hoodies, long pants
    • Rain Gear: Lightweight, waterproof clothing
  • Footwear
    • Waterproof Shoes
  • Accessories
    • Sunglasses: For sun protection
    • Sun Hats: Wide-brimmed hats for sun protection in warm weather
    • Scarves: To protect you from the cold wind
    • Gloves/Mittens: Essential for cold weather
    • Warm Hats: Warm hats for insulation in cold weather
    • Umbrellas/Raincoats: For rainy days

September rainfall patterns in Karuizawa

Explore the daily rainfall trends and prepare for Karuizawas September weather 💧

UV exposure in Karuizawa during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️

Quick links

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Location coordinates Where is Karuizawa?

Get accurate weather forecasts for Karuizawa, located at latitude 36.35 and longitude 138.633. Stay updated with localized weather information tailored for Karuizawa.

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