Climate and monthly weather forecast
Karuizawa, Japan

Karuizawa, a resort town resting amid the mountains of Japan's Nagano Prefecture, inherits a humid subtropical climate that is cataloged in the Köppen climate classification as Cfa. This climate type is characterized by a lack of noticeably dry periods and a substantial amount of rainfall all year round.

Upon studying the data, it's evident that Karuizawa sustains remarkably varied temperatures throughout the year. During winters, the average minimum temperature plunges to about -9.5°C (14.9°F) while in summers, the temperature can heat up to almost around 25.5°C (77.9°F). Notably, the relative humidity levels maintain their stability from month to month, wavering between 72% and 88%.

Analysing the rainfall and snowfall figures, revealing that precipitation is a noteworthy aspect of Karuizawa's weather conditions. Precipitation, whether in the form of snow or rain, can be expected in every month of the year, with a peak in the month of June scoring an impressive 187mm (7.36") of rainfall, indicating that the summers aren’t dry as such but rather wet and humid.

Examining sunlight exposure and daylight hours, it's clear that the daylight varies between nearly 10 hours to a bit over 14 hours from winter to summer. Sunshine varies slightly across the year, with the bare minimum being around 3.6 hours in September and the maximum of 6.2 hours occurring in May.

Planning a trip to Karuizawa? Look no further than the months between April to June and September to October. The temperatures during these periods are the most pleasant for outdoor activities, fluctuating from 13.2°C (55.8°F) to 20.5°C (68.9°F), along with a mild to high quantity of sunshine each day, providing perfect opportunities to explore this stunning resort town. However, those who relish the sight of rain may find June, with a hefty 187mm (7.36") of rainfall, a perfect choice.

Traveling to Karuizawa may not be recommended between December to March, especially for those not used to freezing temperatures. The town experiences its harshest chill during these months with the average minimum temperature potentially going down to -9.5°C (14.9°F). Also, if it's sunshine, one desires, December and March offer the least with only 5 hours per day.

The onset of spring happens to bring moderate weather to Karuizawa. From March to May, the weather slowly turns towards warmth, with the average maximum temperature moving from 6.1°C (43°F) to a pleasant 18.2°C (64.8°F). This temperature swing, combined with the display of cherry blossoms, makes spring an attractive season to tourists.

Summer, from June to August, in Karuizawa, imposes high temperatures as high as 25.5°C (77.9°F). However, the season also sees an abundance of rainfall, culminating in 187mm (7.36") in June. Still, the steady daylight hours, extending up to 14.6 hours, provide ample time for activities, making summer a hot but bearably wet season for tourists.

Autumn in Karuizawa, i.e., from September to November, witnesses a steady decrease in temperature and daylight hours. Temperatures oscillate between 20.5°C (68.9°F) and 10.5°C (50.9°F), and daylight hours from 12.4 to 10.3. Despite reduced daylight, Karuizawa sees a blend of cool and warm days, making it a delightful period to enjoy seasonal foliage.

The winter season of Karuizawa, stretching from December to February, brings in temperatures as low as -9.5°C (14.9°F). Snowfall during this period becomes a constant companion, reaching a considerable height of 430mm (16.93") in January. Despite the low average sunshine hours, Karuizawa's winter forms a scenic white paradise, loved by winter enthusiasts and skiers.

A tranquil, frost-bitten beauty describes Karuizawa in January, the heart of the winter season. The winter weather transition is now in full swing with remarkably cold temperatures ranging from minus 9.5°C (49.1°F) to 1.9°C (35.4°F), and a noticeable 290mm (11.42") of snowfall that blankets the streets. Weather in January »

February continues the chilly trend established in January, although with subtle signs of the approaching spring. The month sees an increase in snowfall to 430mm (16.93"), adding more to the serene snowscape of Karuizawa. Outdoor enthusiasts can revel in various winter activities, while photographers might be drawn to the idyllic winter scenery that transforms the city into a pristine silver world. Weather in February »

March indicates the onset of spring, bringing a mild warming trend to Karuizawa. A transition in weather patterns can be observed with a decline in snowfall to 370mm (14.57"), indicating the recession of winter. The city blossoms with the promise of spring as the weather progressively becomes milder, while daylight hours gradually increase. Weather in March »

April denotes the full arrival of spring in Karuizawa. The month witnesses a marked weather transition, with no more snowfall recorded and temperatures rising to 13.2°C (55.8°F) in the daytime. April sees the city transform into a floral paradise as cherry blossoms burst into bloom. Weather in April »

May is a time of comfortable warmth and scenic splendor in Karuizawa. With temperatures that fluctuate between 5°C (41°F) at night and 18.2°C (64.8°F) during the day, the weather lends a sense of tranquility to the thriving city. Weather in May »

June brings the first hints of summer to Karuizawa, characterized by a modest increase in warmth. The month sees rainfall significantly increase to 187mm (7.36"), initiating the wet season. Despite the prevalent showers, there is an unmistakable sense of vitality and excitement in the air as summer activities begin to pick up. Weather in June »

July is the month when summer takes a firm hold in Karuizawa. Weather conditions become warmer, with daytime temperatures climbing to a yearly high of 24°C (75.2°F). An avenue of outdoor summer festivities opens up, as locals and tourists immerse themselves in the city's rich cultural activities. Weather in July »

August experiences the continuation of summer with relatively hot conditions. The warmest monthly temperature is recorded in this period, reaching 25.5°C (77.9°F). The high temperature and humidity make for frequent, lush summer showers, enriching the environment with a fresh, green glow. Weather in August »

September signals the start of autumn in Karuizawa, presenting cooler temperatures and beautiful fall scenery. The decrease in temperature to 20.5°C (68.9°F) during the day and the onset of cooler nights hint at the transition from summer. Weather in September »

In October, Karuizawa fully embraces the autumn season. The daytime temperature further drops to 15.2°C (59.4°F), providing the perfect backdrop for scenic walks and excursions. The city is awash with vibrant fall colors, showcasing a stunning mix of red, orange, and brown hues on the foliage. Weather in October »

November sees a further decline in temperatures, indicating the onset of winter in Karuizawa. A dip in temperatures to minus 1.2°C (34.2°F) at night marks the return of the cold weather. While the cool climate brings an end to the fall foliage, it sets the stage for the upcoming winter wonderland. Weather in November »

December marks the full return of winter in Karuizawa, embracing chillier temperatures and the first signs of snowfall. The temperature range from minus 6.4°C (43.5°F) to 4.8°C (40.6°F), along with snowfall of 160mm (6.3"), lays the groundwork for a pristine snowscape. Weather in December »