Chase the autumn leaves in Japan
Japan is one of these cases which turns into a gold, yellow and orange fairy tale starting from September. And we can honestly say: We cannot imagine a more beautiful season to visit Japan.
Iiyama Weather in September
Thinking of visiting Iiyama in September? Expect high temperatures reaching 25°C (77°F) during the day, dropping to 16°C (61°F) at night. Heavy showers are common during the rainy season.
Rainfall in Iiyama in September
Iiyama is in the rainy season in September, with rain on around 20 days and an average of 209 mm (8.2 in). Rain during the rainy season is significant rather than just light drizzle. Expect proper showers on most rainy days.
Temperature in Iiyama in September
September in Iiyama sees highs of 25°C (77°F) and lows of 16°C (61°F) overnight. September marks the summer season. This gives the month a fairly typical daily rhythm, with warmer afternoons and more comfortable nights. Nights drop to around 16°C (61°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable.
Sunshine in Iiyama in September
With about 128 hours of sunshine, the area enjoys a nice balance of sun and rainy moments, creating a pleasant environment.For Iiyama itself, May generally stands out with the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
Iiyama Temperature in September
Min Temperature
16°C (61°F)
Max Temperature
25°C (77°F)
Chance of Rain
67%
Precipitation
209 mm (8.2 in)
Rainy days
20 days
Humidity
79% *
Sunshine
128 hours *
Percentage Sunshine
*
* Data from: Joetsu, Japan (30 KM, 18 Miles).
Iiyama Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Iiyama - and find the best time to visit.
Daily Historical Temperatures
49-year average (1976-2025)
Based on our historical records, temperatures in Iiyama typically drop from around 28°C (82°F) at the start of September to approximately 23°C (73°F) by the end. Nights are pleasant, with lows typically ranging from 15°C (59°F) to 21°C (70°F).
Average temperatures in September
Daily Historical Precipitation
49-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather records for Iiyama in September
Browse day-by-day weather records for Iiyama spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Iiyama historical weather extremes in September
According to our 20 years of weather records for Iiyama, the following extremes were recorded between 2006 and 2026.
- On September 3, 2020, temperatures climbed to 35°C (95°F), marking the warmest September day on record.
- The coldest September day was on September 30, 2007, with a maximum of 17°C (63°F).
- The lowest overnight temperature recorded in September was 10°C (50°F) (September 28, 2008).
- The heaviest September precipitation occurred on September 16, 2013, when 106 mm (4.2 in) of precipitation fell.
Best Places in Japan in September
Find out more about the weather in Japan and which places have the best travel conditions in this month. See all of Japan in September →
perfect weather
pleasant
tolerable
unpleasant
poor
Perfect weather is subjective. On this map perfect weather has been defined with temperatures between 20°C (68°F) and 29°C (84°F) and not too much precipitation (less than 90 mm (3.5 in) a month).
What to Wear in Iiyama in September
Pleasant temperatures in September mean you can pack light but flexibel pieces. Think cotton t-shirts, comfortable walking shorts, and one warmer layer for evenings. A light sweater or denim jacket works well. Heavy rain is guaranteed, please bring a good poncho and waterproof everything! It won't hurt to bring your sunglasses along, as you'll see some sunny periods.
What To Do in Iiyama in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
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Swimming7/10 -
Camping6/10
Iiyama 3-Day Forecast
More climate data for Iiyama
Temperature Rainfall Sunshine Humidity
See the full Iiyama climate overview or explore weather in Japan.
Popular in September
Where to go in September - average daytime high across popular destinations.
Bucket list
Need travel inspiration? Check out our bucket list articles and be inspired.
Chase the autumn leaves in Japan
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