Elements of the Weather and their Abbreviations

Cloud: Clear (-); Few Clouds (FC); Mostly Cloudy (MC); Overcast (O); Heavily Overcast (HO); Storm Clouds (SC)

Rain: None (-); Mist (M); Light Rain (LR); Steady Rain (SR); Heavy Rain (HR); Downpour (DP); Pounding Rain (PR); Snow Flurries (SF); Light Snow (LS); Snow (S); Heavy Snow (HS); Blizzard (B)

Wind: Calm (-); Gentle Breeze (GB); Breeze (B); Windy (W); Heavy Wind (HW); Gale (G); Storm (S); Violent Storm (VS)

Weather Effects

Heavy Precipitation: Heavy Rain, Downpour, Pounding Rain, Snow and Heavy Snow lightly obscure giving disadvantage on perception checks relying on sight and hearing, give disadvantage on ranged weapon attacks and extinguish open flames. Blizzard heavily obscures all vision beyond 10 feet.

Strong Wind: Windy and Heavy Wind impose disadvantage on ranged weapon attacks and perception checks that rely on hearing, extinguish open flames, disperse fog and make flying very difficult. Gale, Storm and Violent Storm winds make these things impossible.

Weather: Fog- All vision, including darkvision, heavily obscured beyond 10 feet; Hail- 1 in 10 chance hailstones are large enough to do damage. Each 10 minutes in hail make ranged attack roll with a hit dealing 1d4 bludgeoning damage; Lightning- One strike each hour with 1 in 20 chance of hitting random party member if they are outside. Take 1d10xd8 lightning damage. Dexterity save for half damage.

Extreme Cold: Temperature below -10⁰C- At the end of each hour of exposure must succeed on a DC10 Constitution saving throw or gain one level of exhaustion. Creatures with resistance or immunity to cold damage automatically succeed on the saving throw, as do creatures wearing cold weather gear and creatures naturally adapted to cold climates.

Extreme Heat: Temperature above 40⁰C- A creature exposed to this heat and without access to drinkable water must succeed on a Constitution save at the end of each hour or gain one level of exhaustion. The DC is 5 for the first hour and increases by 1 for each additional hour. Creatures wearing medium or heavy armour, or who are clad in heavy clothing, have disadvantage on the saving throw. Creatures with resistance or immunity to fire damage automatically succeed on the saving throw, as do creatures naturally adapted to hot climates.

High Altitude: Traveling at altitudes of 10 000 feet or higher above sea level is taxing for creatures that need to breathe because of the reduced amount of oxygen in the air. Each hour of travel at high altitude counts as 2 hours for the purpose of determining how long that creature can travel. Breathing creatures can become acclimated to a high altitude by spending 30 days or more at this elevation. Breathing creatures cannot become acclimated to elevations above 20 000 feet unless they are native to such environments.