December weather forecastJoetsu, Japan

December

Weather in December

December, the first month of the winter in Joetsu, is also an icy month, with an average temperature fluctuating between 1.1°C (34°F) and 5.8°C (42.4°F).

Temperature

December's onset brings a reduction in the average high-temperature, from a cool 11.8°C (53.2°F) in November to a cold 5.8°C (42.4°F). Joetsu's December nights witness minimal differential from the daytime temperatures, with averages of 1.1°C (34°F).

Humidity

In Joetsu, Japan, the average relative humidity in December is 82%.

Rainfall

In Joetsu, in December, it is raining for 20 days, with typically 141mm (5.55") of accumulated precipitation. Throughout the year, there are 200.6 rainfall days, and 1190mm (46.85") of precipitation is accumulated.

Snowfall

January through April, November and December are months with snowfall in Joetsu. In Joetsu, during December, snow falls for 10.1 days and regularly aggregates up to 267mm (10.51") of snow. In Joetsu, Japan, during the entire year, snow falls for 50.4 days and aggregates up to 1229mm (48.39") of snow.

Sea temperature

In Joetsu, the average seawater temperature in December is 14.5°C (58.1°F).
Note: It is risky to swim in 14.5°C (58.1°F). Temperatures beneath 10°C (50°F) induce rapid cold shock and hyperventilation.

Daylight

December has the shortest days of the year in Joetsu, with an average of 9h and 42min of daylight.
On the first day of December, sunrise is at 06:42 and sunset at 16:30. On the last day of the month, sunrise is at 07:00 and sunset at 16:39 JST.

Sunshine

In December, the average sunshine is 3.4h.

UV index

January and December, with an average maximum UV index of 1, are months with the lowest UV index in Joetsu. A UV Index value of 2, and less, symbolizes a low health risk from exposure to the Sun's UV radiation for the ordinary person.
Note: In December, a daily maximum UV index of 1 leads to the following instructions:
Prolonged sun exposure generally does not trouble most people. However, it is vital to ensure protection for babies, children, and individuals with sensitive skin. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Be informed! The Sun's UV radiation can be nearly doubled due to the reflection from snow.

Updated: Jan 31, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

December temperatures in Joetsu vary between a high-temperature of 5.8°C (42.4°F) and a low-temperature of 1.1°C (34°F). In August, the average heat index (a.k.a. 'real feel', 'feels like'), which factors the actual air temperature with the relative humidity, is calculated to be 32°C (89.6°F).

In Joetsu, Japan, the average relative humidity in December is 82%.

In Joetsu, Japan, in December, during 20 rainfall days, 141mm (5.55") of precipitation is typically accumulated.

In Joetsu, in December, during 10.1 snowfall days, 267mm (10.51") of snow is typically accumulated.

In Joetsu, Japan, in December, the average water temperature is 14.5°C (58.1°F). At temperatures below 10°C (50°F), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 13°C (55.4°F) is not comfortable.

December has the shortest days of the year in Joetsu, with an average of 9h and 42min of daylight.

In December, the average day length is 9h and 40min.

On the first day of December in Joetsu, sunrise is at 06:42 and sunset at 16:30. On the last day of the month, sunrise is at 07:00 and sunset at 16:39 JST.

The average sunshine duration in December in Joetsu, Japan, is 3.4h.

The months with the lowest UV index are January and December, with an average maximum UV index of 1.

In December, the average daily maximum UV index is 1. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unsafe exposure to Sun's UV rays.

Today

Tomorrow

Long-term

Year J F M A M J J A S O N December

Nov

December

Jan

Average high temperature

11.8°C

5.8°C

2.8°C

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

13.1km/h

16.7km/h

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

Average snowfall

Average snowfall days

0.3

10.1

17.4

Average sea temperature

Average daylight

Average sunshine

Average sunshine days

9.4

4.3

Average UV index

Average cloud cover

Average visibility

Average temperature in December
Joetsu, Japan

Average high temperature in December: 5.8°C

The warmest month (with the highest average high temperature) is August (27.8°C).
The month with the lowest average high temperature is January (2.8°C).

Average low temperature in December: 1.1°C

The month with the highest average low temperature is August (20.9°C).
The coldest month (with the lowest average low temperature) is February (-1.9°C).

Average pressure in December
Joetsu, Japan

Average pressure in December: 1017.6mbar

The month with the highest atmospheric pressure is November (1019.2mbar).
The month with the lowest atmospheric pressure is June (1009.2mbar).

Average wind speed in December
Joetsu, Japan

Average wind speed in December: 15.4km/h

The windiest months (with the highest average wind speed) are January and December (15.4km/h).
The calmest months (with the lowest average wind speed) are July and August (7.7km/h).

Average humidity in December
Joetsu, Japan

Average humidity in December: 82%

The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is May (74%).

Average rainfall in December
Joetsu, Japan

Average rainfall in December: 141mm

The wettest month (with the highest rainfall) is July (142mm).
The driest month (with the least rainfall) is May (57mm).

Average rainfall days in December
Joetsu, Japan

Average rainfall days in December: 20 days

The month with the highest number of rainy days is July (21.6 days).
The month with the least rainy days is February (10.3 days).

Average snowfall in December
Joetsu, Japan

Average snowfall in December: 267mm

The month with the highest snowfall is January (466mm).
The months with the least snowfall are May, June, July, August, September and October (0mm).

Average snowfall days in December
Joetsu, Japan

Average snowfall days in December: 10.1 days

The month with the highest number of snowfall days is January (17.4 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

Average sea temperature in December
Joetsu, Japan

Average sea temperature in December: 14.5°C

The best month for swimming (with the highest average sea temperature) is August (27°C).
The coldest month (with the lowest average sea temperature) is March (10.3°C).

Average daylight in December /
Average sunshine in December
Joetsu, Japan

Average daylight in December: 9h and 42min

The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 42min).

Average sunshine in December: 3h and 24min

The month with the most sunshine is August (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 2h and 42min).

Average sunshine days in December
Joetsu, Japan

Average sunshine days in December: 5 days

The month with the most sunshine days is May (15.1 days).
The month with the least sunshine days is January (4.3 days).

Average UV index in December
Joetsu, Japan

Average UV index in December: 1

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).