I added this to my local Pacific Rules:
Weather
Winter effects are limited to Russia, Korea, Japan, Canada, Alaska, the non-jungle areas of China, and the mountains of India. No other area of the Pacific map is affected by Winter.
The Canada and Alaska references are a little silly, but I was trying to be thorough. It is however, very relevant for fighting in Southern China, near Shanghai, and on down through French Indo-China and into Burma.
