Weather of Avernus
The plane of Avernus has weather that could kill the unprepared.
Humidity
Avernus is similar to a desert in that it lacks fresh water. However, there are pockets of humidity after a large battle. Ichor and viscera evaporate in the hot atmosphere and collect in localized areas. They humidity is never comfortable.
| d20 | Humidity |
|---|---|
| 1 | Arid |
| 2-10 | Dry |
| 11-19 | moist |
| 20 | Sticky |
Water consumption double on arid days.
Precipitation
Precipitation refers to not only water falling from the sky in Avernus, it includes all supernatural phenomenon that falls.
| d20 | Precipitation |
|---|---|
| 1-10 | Clear sky |
| 11-14 | Smokey clouds |
| 15-16 | Acid rain |
| 17 | Rust fall |
| 18 | Ichor rain |
| 19 | Blood rain |
| 20 | Fiery clouds |
Wind
Rapid fluctuations in temperature forms strong winds in Avernus.
| d4 | Wind |
|---|---|
| 1 | No wind |
| 2 | Mild wind |
| 3 | Fast wind |
| 4 | Oppressive wind |
Oppressive wind pushes everything downwards
landscape
Terrain
The elevation, texture and material, and water level.
The outcome of rolling on these tables is a prompt rather than exact terrain. Feel free to add or change based on your own game.
Elevation and feature
| d20 | Elevation |
|---|---|
| 1-3 | Flat |
| 4-6 | Hills |
| 7-9 | Mountain |
| 10-11 | Canyon |
| 12-13 | Volcano |
| 14-15 | Vally |
| 16-17 | Mesa |
| 18 | Cliff |
| 19 | Basin |
| 20 | Crater |
Material Composition
| d20 | Composition |
|---|---|
| 1-5 | Dirt |
| 6-9 | Stone |
| 10-14 | Stone gravel |
| 15-16 | Red sand |
| 17 | Bone gravel |
| 18 | Iron sand |
| 19 | Blood sands |
| 20 | Mud |
Rivers
River styx and lava
| d6 | River |
|---|---|
| 1-4 | No river |
| 5 | Styx |
| 6 | Lava |
River Appearance
If there is a river, figure out what it looks like.
| d20 | Loot |
|---|---|
| 1-4 | Narrow stream |
| 5-8 | Winding |
| 9-12 | Braided |
| 13-16 | Lake |
| 17 | Swamp |
| 18 | Delta |
| 19 | Waterfall |
| 20 | Pond |
Disasters
Avernus is a dangerous place. Even the inhabitants will all agree that the most frightening thing in this plane is its weather.
| d100 | Disaster |
|---|---|
| 1-90 | No Disaster |
| 91 | Meteor shower |
| 92 | Locust swarm |
| 93 | Fungus plague |
| 94 | Stygian Flood |
| 95 | Planar disturbance |
| 96 | Arcane Storm |
| 97 | Tornado |
| 98 | Earthquake |
| 99 | Soulburn Wildfire |
| 100 | Volcanic eruption |
You can change the probability to fit your idea of Avernus.
Sheltering from Disasters
The party as a group can make a perception check to spot a safe shelter from any disaster. The effectiveness of the shelter range from half damage from disasters to full protection. The party can make additional perception checks to look for another shelter after 1 minute of travel.
A disaster can last as long and effect an area as large as the DM wishes. However, if you don't like arbitrarily assigning numbers you could roll 1d4 to determine number of hours it lasts, and 1d4 for number of miles it effects.
| Perception check | Shelter capability |
|---|---|
| 9> | Half damage from effects |
| 10-14 | Advantage and half damage against effects |
| >14 | Full protection |
Shelters can be natural canyons, caves, city ruins, or the carcass of a large creatures.
Meteor shower
An all consuming black cloud threaten to swallow the world. From deep within this cloud balls of ash and fire collect and fall to the ground. For ever minute traveled in a meteor shower there is a 5% chance that a meteor falls near the party. Helm can make a vehicle handling check DC 14 to avoid the meteor. On a failure the vehicle takes 10d6 fire damage. A meteor shower lasts for 2d6 hours and moves in all direction at around 100mph.
Locust swarm.
A large swarm of blood sucking insects scour the lands of Avernus to feed. Any creature not indoors or magically protected must make a constitution saving throw or take 2d4 damage for every minute they spend without protection.
Fungus plague.
Spores of brown and green float in the air like dust. Any dead carcass instantly sprout vibrant colored mushrooms. A living creature that breathes the spores in will feel sleepy and sluggish, they must make a CON save DC 13 or become poisoned for the next hour.
Stygian Flood
The river Styx swell in size due to influx of souls or by powerful magica cast in the lower planes. During a flood, the river swells in double, or even triple in it's width unexpectedly.
Creatures on foot must make a DC 17 DEX saving throw to out run the flood. Escaping in a vehicle requires a helm skill check DC 13. A failure does not mean full exposure to river styx.
On on the first failure, creatures are splashed by small drops of the river, losing a piece of memory permanently. (the character or DM decides)
A second failure represents longer exposure to river styx, They forget the name of a loved one and all memories associated with them for the next 7 days.
A third failure time exposes the creature to the full effects of the river. (DC 20 feeblemind)
Success at any point allows the creature to succeed in escaping the sudden flood.
Planar Disturbance.
Portals connecting to other planes or teleportation spells cast on Avernus have a 10% chance of failing. In addition, portals appear randomly and take curious souls to somewhere else or to an adjacent plane.
When a creature steps into a portal, roll a d 20, on a 4 or higher the creature is taken to a random, location in Avernus.
On a 3 the creature is taken to the Wandering Emporium.
On a 2 the creature is taken to the frozen landscape of Cania, taking 4d8 cold damage and return to the original position after 1 minute.
On a 1 the creature is taken to a realm of slime and fungus. Make a WIS saving throw or become poisoned and see vision of death for the next 1d4 days.
Arcane Thunderstorm.
Slow moving blue and red streaks of hot lightning strikes the ground from the sky. Add a d8 to all lighting damage rolls. For each minute spent inside the disaster, roll a d20, on a 18 or higher, the party is struck by lightning, taking 3d8 lightning damage.
Tornado
A strong twister of red fiery embers tear across Avernus. Creatures not under total cover must make strength saving throw DC 16 to hold on to something. A creature that failed takes 2d6 fire damage and lifted up to 100 feet into the air. Vehicles like the demon grinder is heavy enough to stay grounded and can offer advantage to saving throws to its passengers.
Earthquake
The ground cracks and structures break and crumble. Each creature must make a Dexterity saving throw DC 16 to avoid falling debris. On a failure, they take 4d6 bludgeoning damage and are knocked prone, half damage and they are not knocked prone on a success. A creature makes the save every minute in the area of effect of an earthquake.
A creature with nothing above them does not need to make this save.
Soulburn Wildfire
While some inhabitants are completely immune to the burning of fire, they are not immune to the corrupting effects of Avernus wildfire. This blue flames seem to scream as it consumes everything in its path.
Soulburn fire leaps across creature and objects alike to seek out souls. A creature caught in the blaze takes 4d6 necrotic damage at the beginning of each round. A creature that took this damage must make a DEX save DC 14 to put themselves out. Any creature in 10 feet radius must make the same save or take the damage themselves.
Volcano Eruptions
The surface of Avernus is constantly changing supernaturally. Volcanoes appear suddenly and disappear just as fast. The trouble comes when an active volcano moves beside unsuspecting creatures. Make Helm check DC 14 to stir out of the way of exploding volcano or take 2d6 fire damage and 2d6 poison damage as volcanic ash rain down on surrounding creatures.