What to expect
The average high in December is 53 with an average low of 39.
On nights with cloud coverage or rain, the following day is usually warmer, but a clear night usually means a frigid morning.
December has the lowest precipitation average, with 1.8 days a month. This means it is unlikely to rain, but it's going to be cold.
It's a good idea to check the weather forecast
the night before each day of the event to get a better idea of what you're in for.
What to bring:
If you'll be standing in the line before opening or during the first hour or two, it's a good idea to bring a small blanket to sit on
. The ground is cold and sometimes wet, but you're not going to want to stand for hours at a time.
A hot/cold thermos
full of your favorite warm drink can also help pass the time more pleasantly. Starbucks fans: the chain will fill your thermos happily for the charge of a regular in-store cup. (hot thermoses on rakuten
Hot kairos (pocket warmers).
These are available at every Japanese drug and grocery store during the winter and can be bought in a variety of types and styles. There are types that stick to your clothing, types that can be put in your shoes to warm your toes, and non-sticky pocket types. If you sweat easily, avoid the foot-types. When they wear off, your feet will be wet and all that more prone to the chill. It's a good idea to carry some of these unused for later in the day too. Just remember, garbage cans are not widely available at Comiket and anything you bring into the event, you also have to bring OUT of it. (kairo on rakuten
Warm shoe inserts
are also a good idea. You'll be on your feet a lot and if your feet get wet, tired or cold, you're going to be pretty miserable. Most large shoe stores carry special double-thick, lined winter inserts to protect your feet against the cold. Not only will they keep your feet warm, but they'll give you a bit of extra cushion for all the walking you'll have to do. (inserts on rakuten
Cosplayers wearing revealing or thin costumes are probably going to need thermal undergarments
. UNIQLO sells a popular brand of these called "Heattech
", but nearly every department store carries at least 3 or 4 different brands. You can even buy thermals at the convenience store early on in the winter. Pick thermals that will be hidden by your costume and won't buldge out in unsightly places. Keep in mind any binding or support garments you already wear, too.
Consider wearing nude stockings or pantyhose
instead of baring your legs to the wind. When buying socks
for costumes or skirt/dress ensembles, buy the thickest pair that will look appropriate.
Other Things to Consider:
Flu season is just beginning and while there hasn't been a major outbreak yet this year, bird flu has been discovered in part of Japan and shingata influenza (swine flu) still has the potential to knock out anyone who didn't get it last year. Comiket is a great place for outbreaks to begin or spread. If you're running a fever on the morning of the event, please consider your health and the health of others and say home. If you decide to attend even when ill, please wear a flu mask
While the line and cosplay areas are usually frigid, the inside of the the halls are usually much more moderate and sometimes even a little warmer than expected. If you're planning to spend most of your time indoors, you may want to dress in layers that can be easily removed and stored while you walk around.
Public transportation will be SWELTERING. Don't bundle up so tightly that you bake yourself in the train on the way to the event. Again, dress in layers that can be removed.
Good luck, stay warm, and don't get the flu (or give it to anyone else)!