All year round I carry:
Torch
First aid kit (must learn to use that properly sometime

)
Jump leads
Tow rope
wheel brace
Folding shovel
12-volt compressor thingy
waterproof coat
bulb kit
a couple of 12hour chemical light sticks
warning triangle.
If it's subzero i add a Sabre 45 containing:
wooly jumper
down jacket
mittens
wooly hat
waterproof over trousers
small gas stove + FULL gas canister
Ti-lite mug to heat water in
tupperware box containing hot chocolate sachets, cup-a-soups, noodles, choccy bars, oatcakes and snickers bars + lighter + matches + spoon to eat with!!
head torch + spare batteries
2 x 12hour light sticks + 2 x 30 minute high brightness lightsticks
2l of water - replaced weekly.
small kit of 'useful stuff' like gaffa tape, seamgrip, sewing kit (used by a colleague this morning

), 10m of paracord, tinder pouch with tinder, firesteel and another lighter.
I take the rucksack in the house when i get home so the water doesn't freeze
in addition, in the boot I carry
Walking boots + gaiters
Jerven Fjellduken Thermo hunter + hi-vis rescue flag
full size aluminium Snow shovel
Set of Autosocks for the car tyres
I always carry a leatherman and a small torch on my belt.
In my pockets I'll have disposable tissues and at least one lighter.