How cold is it in Tokyo in December?

Hi, I know you've probably seen this question many times. I've checked out the weather in Tokyo for December already, but because I'm from scorchingly hot Singapore, I can't really translate the numbers/Celsius into how cold I'd be feeling. Plus someone told me while the weather in Tokyo isn't too cold in December, the wind chill is quite high so I have to wear more.

Can anybody tell me how many layers of clothing you actually have to wear? Will a long-sleeved cotton top and a leather jacket do? Or must I wear 3 layers, including a thermal layer?

Will wearing one pair of jeans be enough, so do I have to wear long johns underneath?

Please help! I need to know if I have to pack more or buy more clothing! Thanks!!

Early December:
average daytime high: 14 degrees
average nighttime low: 7 degrees

Late December:
average daytime high: 11 degrees
average nighttime low: 3 degrees

This is cool but not cold enough for long johns if you are from Western Europe and North America but for you I would suggest you bring long johns, sweaters, scarves, a thick jacket etc. or be ready to buy them here. Another idea would be to wait until spring.

The answers are written under similar questions you can find by searching keywords, but in the Pacific side of Japan, winter daytimes can be quite sunny, dry and therefore warm. In particular, Tokyo shares a mild climate.

However, as winters are dry here, when the sun goes down it gets very chilly, and needless to say it tends to be cold in commercial districts where skyscrapers block sunlight and the wind tends to blow through narrow streets.

Posters in the past have suggested that it would be handy to carry lots of thin clothes and wear in layers rather than bring a small amount of thick clothes. This does make sense, because a day can be both warm and cold. You also need to keep in mind that stores and restaurants are usually kept very warm. Scarves and gloves are definitely handy.

Locals usually wear no stockings under their jeans, but perhaps thick socks will make you more comfortable. Of course, you can always buy stockings after you arrive in Japan. Disposable pocket-sized warmers are also available at drug stores. Ask for "kairo". I'm a local, but I can't live without them in winter.