Wind

Wind is a mechanism in Terraria which influences the movement of various objects, as well as the occurance of Windy Days and Sandstorms.

Wind speed ranges between 0 and 60 mph. The wind can blow from either the west or east. Informational accessories such as the Weather Radio show the direction the wind is blowing from, not towards (so for example, "25 mph W" means that the wind is blowing 25 mph from the west).

Wind primarily affects things that have no effect on gameplay, such as cloud movement speeds, blizzard and sandstorm background effects, and the animations of the surface of water and trees. However, it occasionally plays a part in how the game plays, such as its effects on Detonating Bubbles and its effects on players afflicted with Mighty Wind. The UFO Mount summoned by the Cosmic Car Key also seems to be slightly pushed by wind, but it is unnoticeable unless firing a weapon that bounces at a corner for a long period of time.

The Windy Day event occurs when the wind speed is 20 mph or higher, and ends when wind speed decreases below 16 mph.

The Weather Radio, Fish Finder, PDA, Cell Phone, and Shellphone all list the wind speed in the upper right corner of the screen.

Functionality

There are two core values in the code that control wind speed: windSpeedCurrent and windSpeedTarget, both of which are updated each tick. The speed at which windSpeedCurrent changes is determined by the following formula:

speed = |windSpeedTarget/50 * (1 + rain intensity * 5/9) - windSpeedCurrent/50| * 0.0015;

where windSpeedTarget and windSpeedCurrent are in the mph values used by the game. The game stores both values as float values, where < 0 is eastward wind, and > 0 is westward wind. When a world is created, it will generate with winds up to but not exceeding 20 mph, and a variable windCounter is set to prevent changes for the next 15 - 45 seconds. After this period is over, there are a series of random chances that the wind will increase or decrease by up to a certain amount, which occurs on loop every 15 - 45 seconds (a "gust").

Chance	Target wind speed change
25%	-1.25 mph to 1.25 mph
37.5%	-2.5 mph to 2.5 mph
37.5%	-5 mph to 5 mph

A second counter (extremeWindCounter) decreases by one each time a gust occurs. When it hits zero, it causes an "extreme gust". It is both reset on world generation and when an extreme gust is triggered.

Chance	Occurance
21.66%	Target wind is set to 0, and no gusts will occur for the next 2 - 8 minutes.
21.66%	Target wind increases by -10 mph to 10 mph
36.83%	Target wind increases by -20 mph to 20 mph
19.85%	Target wind increases by -40 mph to 40 mph

When an extreme gust occurs, the target wind speed will dictate how many more gusts it will take for another extreme gust to occur.

Target wind speed	Amount of gusts until an extreme gust
0 - 15 mph	10 - 30 gusts
> 15 mph	15 - 40 gusts
> 25 mph	20 - 50 gusts
> 35 mph	25 - 60 gusts

Finally, if a gust has flipped the direction of the wind, there is a 66% chance that the target wind speed will flip its direction back to the original direction it was facing in. After all these steps, the target wind speed is capped to 40 mph.

Effects

Wind affects the following:

Object	Effect
Windy Day	Event occurs when wind speed is 20 mph or higher in any direction.
Sandstorm	Has a chance to occur when wind speed is 30 mph or higher in any direction.
Windy Balloon	Affects movement direction and spawn location. Spawn rate will increase with increased wind speeds.
Angry Dandelion	Affects the direction, animation and movement of fired projectiles, and the animation of the enemy itself. The enemy can only fire in the direction the wind is moving. Spawn rate will increase with increased wind speeds.
Ladybug	Affects movement direction; Will only spawn if the winds exceed 20 mph in any direction.
Ecto Mist	Affects movement direction.
Release Doves	Affects movement direction.
Kites	Pushes when not behind walls.
Water	Affects animation, distortion when Waves Quality is enabled.
Music Box	Affects note drift direction.
Silly Balloon Machine	Affects balloon movement.
Precipitation (Rain, Blizzard, Sandstorm, etc)	Affects particle movements.
Clouds	Affects drift direction.
Bubbles	Affects drift direction.
Detonating Bubble	Affects drift direction.
Angry Tumbler	Pushes.
Party Background Balloons	Affects balloon drift direction.
Players with the Mighty Wind debuff	Pushes.
North Pole Snowflakes	Affects drift direction.
Paper Airplanes	Carries.
Snake Charmer's Flute	Affects the notes spawned by the usage of the flute.
Ambient entities	Affects the movement of lost kites, groups of butterflies, the pegasus, pixie posses, vultures, groups of birds, seagull groups, gastropod groups, balloon slime groups, hellbat groups, bat groups, wyverns, air balloons and airships in the background.
Chimney	Pushes the smoke particles that it emits.
Firefly / Lightning Bug	Will not spawn if the winds exceed 20 mph in any direction.
Butterfly	Will not spawn naturally or from shaken trees if the winds exceed 20 mph in any direction.
Water Striders	Will not spawn naturally if the winds exceed 10 mph in any direction.
Witch's Broom	Pushes the small light on the tip of the handle.
Trees and Living Tree Leaf Blocks	Leaves are dropped with increasing frequency with increasing wind speeds. Said leaves are also affected by wind.
Treetops	Animates the tops of trees with leafy tops.
Vines	Pushes.
Lantern Night Background Lanterns	Affects drift direction.
Release Lantern	Affects drift direction.
Wind ambience track	Affects volume. Only plays if the windspeed is greater than 20 mph.
Waterfalls	Affects animation.
Pin Wheel	Affects spin animation.
Pin Flags	Affects animation speed.
Weather Vane	Affects animation.

Furniture

Some furnitures are affected by wind when on the surface and either in front of any of the following walls, or behind no wall at all.

• Boreal Wood Fence
• Ebonwood Fence
• Lead Fence
• Iron Fence
• Wooden Fence
• Palm Wood Fence
• Pearlwood Fence
• Rich Mahogany Fence
• Shadewood Fence
• Wrought Iron Fence
• Bamboo Fence

The following furnitures are affected by wind when the above conditions are met.

• Chandeliers
• Lanterns
• Pigronata
• Disco Ball
• War Table Banner
• Hanging Pot
• Hanging Brazier
• All Tall Grasses
• Mushrooms
• Acorns
• Vile Mushroom
• Jungle Spores
• Nature's Gift
• Glowing Mushroom
• Herbs
• Vicious Mushroom
• Strange Plants
• Lime Kelp
• Blue Berries
• Yellow Marigold
• Sky Blue Flower
• Green Mushroom
• Teal Mushroom
• Oasis Plants
• Gemcorns
• Sakura Saplings
• Yellow Willow Saplings
• Sunflowers
• Sea Oats

Mighty Wind

• Mighty Wind by default will push players mph * 0.0012 pixels per second. If the wind speed is > 25mph, then this value increases by 37%. If the player is falling or jumping, this value increases by 50%. Finally, if the player moves left or right, this value is decreases by 20%, and will be capped at 0.072 pixels per frame.
• Running into opposing wind with enough speed will cause the player to emit particles similar to the effect of running with Hermes Boots.
• Moving left or right on a mount while at a stationary height negates the effects of mighty wind.

Notes

• At exactly 0 mph, the game will prefer westward wind, but due to the decimal system used for wind speeds, this value will often be near, but not exactly 0.
• On the title screen, wind is initialized with speeds up to 40 mph. This will not carry over to generated worlds, however, which will instead start with winds up to 20 mph.
  • Due to the these initial speeds, there is a 1/400 chance that the world will spawn with a Windy Day in progress.
• Winds will decrease to zero during Lantern Nights, provided the player is not controlling the windspeed with Journey Mode.
• Only the target wind speed will be saved with a world, and when the same world is loaded the current wind speed will be set to the target. This can cause slight differences in wind speeds when a player exits and re-enters a world.

Trivia

At lower wind speeds, the leaves drop with a lower frequency from trees each tick (5 mph → 1/2000 chance, 10 mph → 1/1000, 15 mph → 1/450, ... 40 mph → 1/50). While the maximum speed is 40mph, however, there is code for cases up to and exceeding 55 mph, with chances being as low as 1/10 each tick.

Scrapped Projectile Physics

In the game code, there is a boolean Main.windPhysics that triggers a feature where projectiles would be affected by wind. As it is disabled, there is no such feature in the game currently. Below is a detailed description of the feature's effects.

Notably, this feature would attempt to disable wind effects on the North Pole, however it is unknown if this was to prevent conflict with existing code or to remove the feature outright.

When the feature is active, all projectiles below, when on the surface, and not stuck in tiles or behind walls, will be affected by wind. This occurs only if they are moving against the current wind direction, or if their x velocity is less than wind mph * 0.36. This will change their x velocity by wind mph * 0.002 pixels per tick, or wind mph * 0.12 pixels per second.

A projectile's x velocity in this state cannot exceed 16, but this limit is never reached as the max possible wind speed, 40 mph, can only push projectiles up to 14.4 pixels per tick.

Quarter Note Internal Projectile ID: 76 Eighth Note Internal Projectile ID: 77 Tied Eighth Note Internal Projectile ID: 78 Crystal Shard Internal Projectile ID: 90 Icewater Spit Internal Projectile ID: 177 Crystal Charge 1 Internal Projectile ID: 521 Crystal Charge 2 Internal Projectile ID: 522 Beach Ball Internal Projectile ID: 155 Flare Internal Projectile ID: 163 Blue Flare Internal Projectile ID: 310 Red Firework Rocket Internal Projectile ID: 167 Green Firework Rocket Internal Projectile ID: 168 Blue Firework Rocket Internal Projectile ID: 169 Yellow Firework Rocket Internal Projectile ID: 170 Red Firework Rocket Internal Projectile ID: 415 Green Firework Rocket Internal Projectile ID: 416 Blue Firework Rocket Internal Projectile ID: 417 Yellow Firework Rocket Internal Projectile ID: 418 Rope Coil Internal Projectile ID: 171 Vine Rope Coil Internal Projectile ID: 475 Silk Rope Coil Internal Projectile ID: 505 Web Rope Coil Internal Projectile ID: 506 Explosive Bunny Internal Projectile ID: 281 Bubble Internal Projectile ID: 410 Nail (friendly) Internal Projectile ID: 514 Ichor Splash Internal Projectile ID: 524 Spore Gas Internal Projectile ID: 569 Spore Gas 2 Internal Projectile ID: 570 Spore Gas 3 Internal Projectile ID: 571 Wooden Arrow (friendly) Internal Projectile ID: 1 Fire Arrow Internal Projectile ID: 2 Unholy Arrow Internal Projectile ID: 4 Jester's Arrow Internal Projectile ID: 5 Bullet Internal Projectile ID: 14 Meteor Shot Internal Projectile ID: 36 Harpy Feather Internal Projectile ID: 38 Hellfire Arrow Internal Projectile ID: 41 Seed Internal Projectile ID: 51 Stinger Internal Projectile ID: 55 Wooden Arrow (hostile) Internal Projectile ID: 81 Flaming Arrow Internal Projectile ID: 82 Holy Arrow Internal Projectile ID: 91 Poison Dart Internal Projectile ID: 98 Cursed Arrow Internal Projectile ID: 103 Bone Arrow Internal Projectile ID: 117 Frost Arrow Internal Projectile ID: 120 Copper Coin Internal Projectile ID: 158 Silver Coin Internal Projectile ID: 159 Gold Coin Internal Projectile ID: 160 Platinum Coin Internal Projectile ID: 161 Frostburn Arrow Internal Projectile ID: 172 Ice Spike Internal Projectile ID: 174 Jungle Spike Internal Projectile ID: 176 Confetti Internal Projectile ID: 178 Deadeye Bullet Internal Projectile ID: 180 Poison Dart Internal Projectile ID: 184 Pygmy Spear Internal Projectile ID: 195 Chlorophyte Bullet Internal Projectile ID: 207 Chlorophyte Arrow Internal Projectile ID: 225 High Velocity Bullet Internal Projectile ID: 242 Stynger Internal Projectile ID: 246 Flower Pow Petal Internal Projectile ID: 248 Eye Beam Internal Projectile ID: 259 Poison Fang Internal Projectile ID: 265 Poison Dart Internal Projectile ID: 267 Skull Internal Projectile ID: 270 Seed Internal Projectile ID: 275 Poison Seed Internal Projectile ID: 276 Ichor Arrow Internal Projectile ID: 278 Ichor Bullet Internal Projectile ID: 279 Venom Arrow Internal Projectile ID: 282 Venom Bullet Internal Projectile ID: 283 Party Bullet Internal Projectile ID: 284 Nano Bullet Internal Projectile ID: 285 Explosive Bullet Internal Projectile ID: 286 Golden Bullet Internal Projectile ID: 287 Confetti Internal Projectile ID: 289 Candy Corn Internal Projectile ID: 311 Jack 'O Lantern Internal Projectile ID: 312 Stake Internal Projectile ID: 323 Flaming Wood Internal Projectile ID: 325 Pine Needle (friendly) Internal Projectile ID: 336 Blizzard Internal Projectile ID: 337 Pine Needle (hostile) Internal Projectile ID: 345 Missile Internal Projectile ID: 350 Venom Fang Internal Projectile ID: 355 Pulse Bolt Internal Projectile ID: 357 Hornet Stinger Internal Projectile ID: 374 Imp Fireball Internal Projectile ID: 376 Mini Retina Laser Internal Projectile ID: 389 Mini Sharkron Internal Projectile ID: 408 Meteor 1 Internal Projectile ID: 424 Meteor 2 Internal Projectile ID: 425 Meteor 3 Internal Projectile ID: 426 Laser Internal Projectile ID: 440 Bee Arrow Internal Projectile ID: 469 Web Spit Internal Projectile ID: 472 Bone Arrow Internal Projectile ID: 474 Crystal Dart Internal Projectile ID: 477 Cursed Dart Internal Projectile ID: 478 Ichor Dart Internal Projectile ID: 479 Seedler Thorn Internal Projectile ID: 484 Hellwing Internal Projectile ID: 485 Shadowflame Arrow Internal Projectile ID: 495 Nail (hostile) Internal Projectile ID: 498 Javelin (friendly) Internal Projectile ID: 507 Javelin (hostile) Internal Projectile ID: 508 XBone Internal Projectile ID: 532 Poison Spit Internal Projectile ID: 572 Alien Goop Internal Projectile ID: 581 Skull Internal Projectile ID: 585 Paintball Internal Projectile ID: 587 Slime Spike Internal Projectile ID: 605 Vortex Rocket Internal Projectile ID: 616 Luminite Bullet Internal Projectile ID: 638 Javelin Internal Projectile ID: 662 Javelin Internal Projectile ID: 685 Drakin Shot Internal Projectile ID: 671 Ogre Spit Internal Projectile ID: 676 Ballista Shot Internal Projectile ID: 680 Withering Bolt Internal Projectile ID: 682 Betsy's Fireball Internal Projectile ID: 686 Phantom Phoenix Internal Projectile ID: 706 Aerial Bane Internal Projectile ID: 710 Betsy's Wrath Internal Projectile ID: 711 Tome of Infinite Wisdom Internal Projectile ID: 712 Queen Bee's Stinger Internal Projectile ID: 719 Rolling Cactus Spike Internal Projectile ID: 763 Geode Internal Projectile ID: 772 Blood Shot Internal Projectile ID: 811 Blood Nautilus Shot Internal Projectile ID: 814 Blood Rain Internal Projectile ID: 819 Skull Internal Projectile ID: 837 Zapinator Internal Projectile ID: 876 Crystal Spike Internal Projectile ID: 920 Bouncy Gel Internal Projectile ID: 921 Regal Gel Internal Projectile ID: 926 Volatile Gelatin Internal Projectile ID: 937 Shuriken Internal Projectile ID: 3 Bone Internal Projectile ID: 21 Throwing Knife Internal Projectile ID: 48 Poisoned Knife Internal Projectile ID: 54 Holy Water Internal Projectile ID: 69 Unholy Water Internal Projectile ID: 70 Blood Water Internal Projectile ID: 621 Magic Dagger Internal Projectile ID: 93 Cannonball (friendly) Internal Projectile ID: 162 Snow Ball (friendly) Internal Projectile ID: 166 Cannonball (hostile) Internal Projectile ID: 240 Stynger Shrapnel Internal Projectile ID: 249 Paladin's Hammer (hostile) Internal Projectile ID: 300 Vampire Knife Internal Projectile ID: 304 Rotten Egg Internal Projectile ID: 318 Star Anise Internal Projectile ID: 330 Ornament Shrapnel Internal Projectile ID: 347 Love Potion Internal Projectile ID: 370 Foul Potion Internal Projectile ID: 371 Bone Internal Projectile ID: 471 Shadowflame Knife Internal Projectile ID: 497 Flask Internal Projectile ID: 501 Spark Internal Projectile ID: 504 Toxic Flask Internal Projectile ID: 510 Frost Daggerfish Internal Projectile ID: 520 Bone Dagger Internal Projectile ID: 599 Football Internal Projectile ID: 861 Tree Globe Internal Projectile ID: 868 World Globe Internal Projectile ID: 869 Rock Internal Projectile ID: 909 Sparkle Slime Balloon Internal Projectile ID: 936 Ball of Fire Internal Projectile ID: 15 Cursed Flame (friendly) Internal Projectile ID: 95 Cursed Flame (hostile) Internal Projectile ID: 96 Ball of Frost Internal Projectile ID: 253 Meowmere Internal Projectile ID: 502 Dirt Ball Internal Projectile ID: 17 Sand Ball Internal Projectile ID: 31 Mud Ball Internal Projectile ID: 39 Ash Ball Internal Projectile ID: 40 Sand Ball Internal Projectile ID: 42 Ebonsand Ball Internal Projectile ID: 56 Ebonsand Ball Internal Projectile ID: 65 Pearlsand Ball Internal Projectile ID: 67 Pearlsand Ball Internal Projectile ID: 68 Silt Ball Internal Projectile ID: 71 Snow Ball (hostile) Internal Projectile ID: 109 Slush Ball Internal Projectile ID: 179 Crimsand Ball Internal Projectile ID: 241 Crimsand Ball Internal Projectile ID: 354 Copper Coins Internal Projectile ID: 411 Silver Coins Internal Projectile ID: 412 Gold Coins Internal Projectile ID: 413 Platinum Coins Internal Projectile ID: 414 Blue Dungeon Debris Internal Projectile ID: 736 Green Dungeon Debris Internal Projectile ID: 737 Pink Dungeon Debris Internal Projectile ID: 738 Shell Pile Internal Projectile ID: 812 Spiky Ball Internal Projectile ID: 24 Glowstick Internal Projectile ID: 50 Sticky Glowstick Internal Projectile ID: 53 Beenade Internal Projectile ID: 183 Spiky Ball Internal Projectile ID: 185 Smoke Bomb Internal Projectile ID: 196 Boulder Internal Projectile ID: 261 Thorn Ball Internal Projectile ID: 277 Greek Fire 1 Internal Projectile ID: 326 Greek Fire 2 Internal Projectile ID: 327 Greek Fire 3 Internal Projectile ID: 328 Ornament (hostile) Internal Projectile ID: 346 Spike Internal Projectile ID: 352 Spider Egg Internal Projectile ID: 378 Molotov Fire 1 Internal Projectile ID: 400 Molotov Fire 2 Internal Projectile ID: 401 Molotov Fire 3 Internal Projectile ID: 402 Saucer Scrap Internal Projectile ID: 450 Spelunker Glowstick Internal Projectile ID: 473 Cursed Dart Flame Internal Projectile ID: 480 Seedler Nut Internal Projectile ID: 483 Bouncy Glowstick Internal Projectile ID: 515 Twinkle Internal Projectile ID: 538 Fairy Glowstick Internal Projectile ID: 870 Drippler Crippler (extra ball) Internal Projectile ID: 928 Cluster Rocket I Internal Projectile ID: 776 Cluster Grenade I Internal Projectile ID: 777 Cluster Proximity Mine I Internal Projectile ID: 778 Cluster Fragments I Internal Projectile ID: 779 Dry Grenade Internal Projectile ID: 800 Dry Proximity Mine Internal Projectile ID: 801 Cluster Rocket I Internal Projectile ID: 803 Cluster Rocket II Internal Projectile ID: 804 Wet Rocket Internal Projectile ID: 805 Lava Rocket Internal Projectile ID: 806 Honey Rocket Internal Projectile ID: 807 Mini Nuke Rocket I Internal Projectile ID: 808 Mini Nuke Rocket II Internal Projectile ID: 809 Dry Rocket Internal Projectile ID: 810 Bomb Internal Projectile ID: 28 Dynamite Internal Projectile ID: 29 Grenade Internal Projectile ID: 30 Sticky Bomb Internal Projectile ID: 37 Happy Bomb Internal Projectile ID: 75 Skeletron Prime Bomb Internal Projectile ID: 102 Explosives Internal Projectile ID: 108 Grenade I Internal Projectile ID: 133 Rocket I Internal Projectile ID: 134 Proximity Mine I Internal Projectile ID: 135 Grenade II Internal Projectile ID: 136 Rocket II Internal Projectile ID: 137 Proximity Mine II Internal Projectile ID: 138 Grenade III Internal Projectile ID: 139 Rocket III Internal Projectile ID: 140 Proximity Mine III Internal Projectile ID: 141 Grenade IV Internal Projectile ID: 142 Rocket IV Internal Projectile ID: 143 Proximity Mine IV Internal Projectile ID: 144 Landmine Internal Projectile ID: 164 Rocket Internal Projectile ID: 303 Snowman Rocket I Internal Projectile ID: 338 Snowman Rocket II Internal Projectile ID: 339 Snowman Rocket III Internal Projectile ID: 340 Snowman Rocket IV Internal Projectile ID: 341 Sticky Grenade Internal Projectile ID: 397 Sticky Dynamite Internal Projectile ID: 470 Bouncy Bomb Internal Projectile ID: 516 Bouncy Grenade Internal Projectile ID: 517 Bomb Fish Internal Projectile ID: 519 Confetti Grenade Internal Projectile ID: 588 Bouncy Dynamite Internal Projectile ID: 637 Goblin Bomb Internal Projectile ID: 681 Scarab Bomb Internal Projectile ID: 773 Cluster Fragments I Internal Projectile ID: 862 Cluster Fragments II Internal Projectile ID: 863 Wet Bomb Internal Projectile ID: 903 Lava Bomb Internal Projectile ID: 904 Honey Bomb Internal Projectile ID: 905 Dry Bomb Internal Projectile ID: 906 Dirt Bomb Internal Projectile ID: 910 Sticky Dirt Bomb Internal Projectile ID: 911 Santank Rocket Internal Projectile ID: 930 Tombstone Internal Projectile ID: 43 Grave Marker Internal Projectile ID: 201 Cross Grave Marker Internal Projectile ID: 202 Headstone Internal Projectile ID: 203 Gravestone Internal Projectile ID: 204 Obelisk Internal Projectile ID: 205 Golden Cross Grave Marker Internal Projectile ID: 527 Golden Tombstone Internal Projectile ID: 528 Golden Grave Marker Internal Projectile ID: 529 Golden Gravestone Internal Projectile ID: 530 Golden Headstone Internal Projectile ID: 531

Functionality

There are two base values the game uses when determining windspeed, "windSpeed" and "windSpeedSet". windSpeedSet is a value set to determine what value windSpeed should gradually change to, but both values are used intermittently throughout the code to affect certain objects. The game takes the following steps to determine windSpeed:

• If windSpeed is not already equal to windSpeedSet, move it closer by .001
• Change windSpeedSpeed by a value from -.001 to .001 (-.002 to .002 when night)
• Cap windSpeedSpeed to -.002 or .002
• Change windSpeedTemp by windSpeedSpeed (windSpeedSpeed x 2 if raining)
• Cap windSpeedTemp by .3 + .5 * (Percentage cloud cover / 100)
• Set windSpeedSet to windSpeedTemp
• Loop

Overall this means that there are stronger wind speeds when it is nighttime and/or raining. However, as sandstorms do not count as rain, sandstorms do not actually cause increased wind speeds. Also notable is that more clouds in the sky means higher potential for higher wind speeds, whether it is raining or not.