Weather Rules  - Keep in mind racial/class bonuses.  Some races/classes are immune.

Wind every 15mph is a -1 perc

Cold approaching zero, every ten(10) degrees below 40 must be countered with proper
clothing or suffer -1
dexterityunder zero every 5 degrees is an additional -1 dexterity

EXAMPLE: At -12 degrees with no protective clothing you would suffer -5 plus -3 dex, for a
-8 total
Dexterity penalty.

Frostbite can occur within minutes.  At 10 degrees or below all characters with no protective clothing will take 25 Constitution damage per hour.

EXAMPLE: with 8 constitution you would take 17 damage an hour.

Heat after (constitution/3 hours) suffer -1 strength penalty per hour of heat exceeding 100degrees.