Why was it so cold today?

I think because it's November and that's really close to December.

December is a little bit cold. I think this is the reason for the extreme winter cold.

Winter is icummen in. Lhude sing Goddamm.

WRONG FORUM. Epic Fail. Reported. 

Daily temperature fluctuations are mostly the results of air currents which bring in warm or cold air.  Cloud cover also impacts the amount of solar radiation reaching the ground and tends to make things cooler.

It is to do with the weather.

Winter is Coming!

Since it is now around 11 am in the UK you must be writing from eastern Asia or the Far East if you use "was". That part of the world varies from almost Arctic to tropical, so please tell us which part you are asking about.

Artic air coming down.

Sadly, it's winter time. I hate it!!!!!!!