Karuizawa in December: weather, what to wear and what's on

Averages for 1991–2020 at the JMA's Karuizawa station (999 m above sea level).

High

5.3°C (42°F)

Low

−5.3°C (22°F)

Precipitation

29.6 mm

Wet days

5.0 days

Sunshine

172 hours

Snow on ground

7.9 days

• Highs fall 5.9°C from November and drop another 3.0°C into January.
• That is 9.3°C below Karuizawa's yearly average high of 14.6°C.
• Of our 34 places with temperature records, Karuizawa is the 6th coldest in December: 0.6°C cooler than Shirakawa-go and 0.2°C warmer than Nasu.
• Of our 35 places, Karuizawa gets the least precipitation in December: 14.5 mm less than Sendai.
• Rain or snow of 1 mm or more falls on 5.0 days, and 10 mm or more on 0.9 days.
• The temperature drops below 0°C on 29.3 nights.
• On 2.3 days it stays below 0°C all day.
• 19 cm of snow falls in an average December; snow lies on the ground on 7.9 days.
• The sun is out for 40% or more of the possible hours on 22.9 days, and 2.0 days have under 0.1 hours of sunshine.

Average temperature

−0.5°C (31°F)

Humidity

78%

Deepest snow (average of each year's deepest)

12 cm

Early, mid and late December

By the last ten days of December the average high in Karuizawa is 3.2°C lower than in the first ten.

Is Karuizawa cold in December?

Yes, it is cold. Karuizawa averages 5.3°C (42°F) by day and −5.3°C (22°F) at night in December. It gets colder still: 21–31 January has highs of 2.0°C.

Cold: highs around 5.3°C

• A winter coat over layers, and a scarf.
• Gloves and a hat for mornings and nights: the temperature drops below 0°C on 29.3 nights.
• A waterproof jacket with a hood: rain or snow falls on 5.0 days.

Shoes

• Waterproof boots with good grip: snow lies on the ground on 7.9 days (deepest 12 cm on average).

Pack

• Waterproof jacket with a hood
• Gloves and a warm hat
• Scarf
• Waterproof boots with grip

• Our clothing rules

There are no national holidays in December 2026.

In December 2025, hotels and inns across Nagano Prefecture were 33.3% full on average (10th busiest of 12 months). Foreign guests spent 303,720 nights there that month (Japan Tourism Agency). That compares with 37.4% in November and 38.3% in January.

• Japan in December: visitor numbers and busy travel days
• Holidays in December
• Year-end and New Year holidays