Nagano Weather in September

Season: Late Summer ~ Early Autumn
In Brief: Cool; Slightly Cold Early Mornings & Nights in Mountains

In Nagano, September brings the final touch of summer, featuring a pleasant coolness and moderate rainfall, ideal for escaping the summer heat. As the month winds down, you will see farmers working in the golden rice paddies, showcasing the autumn harvest.

Golden Leaves in September, Nagano

Temperature

Avg. Temp. Range: 15~24℃/59~75℉

Nagano experiences cool weather in September, with daytime temperatures hovering around 30°C (86°F) and dipping to 25°C (77°F) towards the end of the month, a notable 7-10°C (13-18°F) cooler than Tokyo. Nights are cooler, ranging from 15-20°C (59-68°F). 

In the mountains, daytime temperatures are mild at 20°C (68°F), but nights can be chilly, dropping to 10°C (50°F), showcasing the significant temperature variation.

Precipitation

Rainfall: 130 mm

Avg. Rainy Days: 12

In Nagano, September sees moderate rainfall, with downtown experiencing about 5 rainy days and the mountains around 10. The showers are generally light to moderate and last under 2 hours. After rain, temperatures fluctuate significantly, making thermal clothing a must.

Sunrise & Sunset

In Nagano, September offers about 12.5 hours of daylight, with sunrises from 5:18 to 5:41 and sunsets from 17:32 to 18:15, perfect for exploring diverse activities. Sunny days bring intense sunlight, and nights reveal a dazzling sky filled with stars.

Note: Nagano's autumn begins in late September with only a slight temperature drop, leading to little maple leaf color. The best months for viewing the foliage are October and November.

Holidays this Month: Aged Day & Autumnal Equinox Day

September features two national holidays: Aged Day, offering 3 days off, and Autumnal Equinox Day, a 1-day holiday. Many Japanese combine these with weekends and 4-5 days of annual vacation for a lengthy 10-day break.

In 2025, Aged Day runs from September 13-15, followed by Autumnal Equinox Day on September 23. Expect a slight tourism boom from the 13th to the 23rd. Popular holiday destination Nagano will likely be crowded and pricey. Plan your itinerary wisely to avoid the crowds, and book early for better, more affordable options.

Packing List

Upper Body

Wear short T-shirts and sunproof jackets during the daytime, and hoodies and thick jackets in the evening. In Nagano's mountains, you may need a light down jacket after 8 PM.

Bottoms

Take short pants and light long pants. Warm long pants are more practical for nights in the mountains.

Shoes

Sports shoes and canvas shoes are convenient in September.

Accessories

Apply sunscreen and wear hats to prevent sunburn. Since bears are active now, take bear bells for safety.

Rain Gear

Raincoats, umbrellas, and rain boots are necessary in September in Nagano.

Top Things to Do in September in Nagano

Beat the Heat in Karuizawa

Hike in Karuizawa

With only about five rainy days and comfortable temperatures for its elevated location, Karuizawa offers a serene escape. As you wander through charming wooden houses, you'll be surrounded by abundant greenery, including stunning trees, expansive grasslands, and serene lakes, all cooled by refreshing breezes.

Join in the Harvest in Nagano (Late September)

Nagano Paddies in September

At the end of the month, Nagano's paddies glow with vibrant gold. The Inagura Rice Terraces, ranking among Japan's Top 100 terraced rice fields, display heavy, ripe rice spikes. Farmers in wide-brimmed hats diligently harvest the crop, and visitors are welcome to join in after seeking permission. While there, you can bring home a piece of the experience with local sake from nearby specialty stores.

Be a Ninja in Togakushi 

Experience Nagano Ninja Culture

The Togakushi Ninja Museum is a unique spot where you can learn about ninjas (trained Japanese spies and assassins) and immerse yourself in their world. Inside the Ninja Trick Mansion, enjoy a thrilling escape game designed for all ages. Solve a series of clever puzzles in this interactive adventure to find your way out and experience the joy of being a ninja.