Weather

Autumn on the Sword Coast
Temperature:
 * 1-14: Cool; near-60 degrees.
 * 15-17: 1d4x10 degrees above 60. Note discomfort if they remain in their full regular autumn clothes.
 * 18-20: 1d4x10 degrees below 60.
 * At 40 degrees or under, characters without bedroll will have trouble sleeping. On long rest, do not recover 1d4 HP.

Wind:
 * 1-12: None
 * 13-17: Light
 * 18-20: Strong. Physical ranged attacks beyond 30 feet make a -2 to hit.

Precipitation:
 * 1-10: None
 * 10-16: Light Rain
 * 17-20: Heavy rain. Minus to Spot Distance for encounters.

Random Encounters

 * 1) Roll table for likelihood of Encounter
 * 2) Roll Encounter Table for what type of monster.
 * 3) Roll Spot Distance
 * 4) Roll Monster Disposition
 * 5) Determine how the monster reacts to seeing them first, or what the players would spot the monster doing.

Spot Distance
For random encounters, roll Perception. The result = the number of squares the party will notice the other from.

If the party with the higher Perception roll fails to pass their opponent's Passive or Active Stealth roll, the other party sees them at the distance they rolled.

If both fail to beat the other's Passive Stealth, both notice each other at the same time at half the distance of the lower Perception check. If neither beat the other's Active Stealth, the parties miss each other?