From HOI2Wiki

There are six types of weather in Hearts of Iron 2. They are listed below with appropriate notes

Contents 1 Long Term Weather 1.1 Frozen 1.2 Muddy 2 Short Term Weather 2.1 Blizzard 2.2 Raining 2.3 Snowing 2.4 Storm

Long Term Weather

The first two weather states are long term and apply to specific provences at specific times on the year

Frozen

Winter

• Refered to in the movement files as MOV_FROZEN

Muddy

• Refered to in the movement files as MOV_MUDDY

Short Term Weather

The remaining four weather states are tempory and will exist in proviences for a short period of time.

Blizzard

• Refered to in the movement files as MOV_BLIZZARD

Raining

• Refered to in the movement files as MOV_RAIN

Snowing

• Refered to in the movement files as MOV_SNOW

Storm

• Refered to in the movement files as MOV_STORM