The DMG provides rules for rolling weather in D&D 5th edition (DMG Pg 110). They’re straight forward, impossible to remember, and often skipped by DMs. We certainly used to overlook it—but we’ve come to appreciate the weather roll as a crucial part of our sessions.
According to these rules, only 25.2% of days in Faerûn are a seasonally normal temperature, without wind or rain. If you don’t roll for the weather, chances are you’re missing out on the other 35 unique weather states that can occur, with all the complications and benefits they can bring.
Below are all of the weather conditions that can roll in, and the chance that they will occur each day.
It’s important mechanically
There’s a 27.75% chance each day that pounding rain or roaring wind will impose disadvantage on Perception Checks that rely on hearing. There is a 40% chance that there will be rain, extinguishing unprotected flames.
There are entire aspects of the game, spells, rules and class/background features that begin to make a lot more sense with weather in the game. Wood Elf with Mask of the Wild? Heavy precipitation will Lightly Obscure the landscape, giving you all the cover you need to hide. Goliath with Mountain Born? How does that matter unless you have a really, really cold day? Call Lightning does more damage if it’s cast in a storm and any spell with the world ‘Cloud’ in it doesn’t stand a chance in strong wind.
This only scratches the surface of the many spells—Shape Water, Frost Fingers!—and creatures—Fire Elementals, Anything that Flies!—heavily impacted by weather conditions.
Wait, anything that flies? Yup. Let’s take a closer look at the rules the DMG lays out for Weather Effects.
Wind can affect a lot about the environment. Scent can carry a long way on the wind. Smoke from fires may be blown through the air or dispersed. Insects, spores, or gasses that may normally cloud the air will be absent.
Strong Wind (15% Chance to occur)
How does precipitation change following tracks? Are the players traveling over a surface that becomes difficult terrain when wet? Are traps harder to spot when covered in a light layer of snow?
Heavy Precipitation (15% Chance to occur)
Depending on the climate, Extreme Heat and Extreme Cold can be a common occurrence. Perhaps everyone in town has all of their windows wide open due to the extreme heat, or a distant camp is revealed by the smoke rising from fires kept roaring for warmth.
Extreme Cold (3.75–15% Chance to occur)
Extreme Heat (3.75–15% Chance to occur)
We’re always after fun at our table. Rolling weather allows players to bring out those lesser used aspects of their characters. They will get creative about how they’re using the weather to their advantage, or adjusting their plans to the new, random challenge. A particularly bad day of weather can add an additional layer of strategy to encounters, or an opportunity for a character to shine in a new way. Does it matter if Tenser’s Floating Disk can shield a bonfire from the rain? It might be crucial.
For the DM, weather is a beautifully simple keystone to the adventuring day. Describing the weather bolsters immersion with a few sentences. It punctuates the day with a transition during an otherwise uneventful watch—“you feel the air get cooler as clouds roll in.” Weather is a detail that you don’t have to write, but adds a dynamic variable that will affect every decision a party makes. On a deeper level, weather is a tie binding the human experience to the fantasy world. Weather is universal.
There’s a reason “it was a dark and stormy night” is both trite and still the way every horror story begins. We all experience the weather; here on Earth as in Torril, or Eberron, or Greyhawk. A quick roll behind the screen and your players gather their equipment, pick up camp, and head off into the morning mist of a new day. Looks like it's going to be a real scorcher.