the weather sets a number of buffs or debuffs depending on the weather
Sunny - temperature is warm. Situational +1 to outdoor perception, survival, and investigation checks.
Cloudy/Overcast - no harsh sunlight. Easier checks to determine next oncoming weather. +1 to stealth or sleight of hand checks.
Rainy - additional damage die on lightning damage.
Snowy - -1 damage die for fire damags.
Thunderstorms - 2 additional damage die for lightning damage. Disadvantage on perception and survival checks.
Tornadoes - active and moving environmental threat. It has the features of the hurricane but takes up a 7 hex circle and travels 1 square in a random direction when the party moves
Hurricane/Typhoons -
The storm that surrounds you has hurricane-force winds spinning in a circle with you at the center. Normal ranged attacks through the hurricane's windy area are impossible, and even heavier projectiles such as siege weapons and giant boulders have disadvantage on the attack roll.
Creatures who move inside the spell's area suffer effects depending on their size and whether they're airborne. Each creature must make a saving throw at the beginning of its turn or when in enters the affected area.
- Medium or smaller creatures must succeed on a Constitution save or be knocked 1d4×10 feet away from the eye of the hurricane's center and take 1d4 points of nonlethal damage per10 feet traveled and fall prone.Flying creatures are blown back 2d6×10 feet and take 2d6 points of nonlethal damage.
- Large creatures must succeed on a Constitution save or be knocked prone by the force of the wind. Flying creatures are instead blown back 1d6×10 feet.
- Huge creatures must succeed on a Constitution save or be blown back 1d4x5 feet. Flying creatures are instead blown back 1d6×5 feet.
- Gargantuan and Colossal creatures can move through the spell's area without adverse consequences.
Winter Storm - -2 damage dice for fire damage. After every hex, party makes a constitution saving throw. Base starts off at DC10, can increase based off other weather factors. Creatures with resistance gain advantage on the saving throw, immunity grants autosuccess. On a failure, one level of exhaustion is gained.
Blizzard - area is heavily obscured. Exposed flames are doused. Party can only move two hexes a day unless a spell or effect circumvents the blizzard. In combat, the floor is difficult terrain. -2 damage dice for fire damage. After every hex, party makes a constitution saving throw. Base starts off at DC10, can increase based off other weather factors. Creatures with resistance gain advantage on the saving throw, immunity grants autosuccess. On a failure, one level of exhaustion is gained.
Drought (harsh sun?) - extreme sun, will give advantage to perception and survival checks to find things. With the high heat, creatures must consume an extra waterskin per day. Half amount for small creatures or those with fire resistant. Double amount for larger than medium or with fire vulnerability. (Additionally for a higher difficulty survival, creatures drink additional waterskin after combat encountered during that day). A creature who doesnt drink makes a DC5 constitution saving throw against exhaustion at the end of each hex, disadvantage if wearing medium or heavy armor or heavy clothing. The DC goes up per hex without resolving the issue.