Weather on Serpent Lake

Blow Me Down: Weather On the High Seas

In describing a scene, the heavy hitters like slathering demons, bubbling lava, and glowing baubles normally take up the lion’s share of the narrative. Weather sounds like something you talk about when you’ve run out of exciting things to mention. Breezy with a couple clouds that look like a puppy chasing a cupcake? Yawn.

Once we introduce mechanical effects, weather could matter, at least in some edge cases. Slick grass, lower visibility, maybe a chance to replenish the waterskins. But what about at sea?

Weather is as important as the dungeon room’s lighting, terrain, and size. Unless you’re simply narrating quick travel, weather is one of the primary mechanical drivers on the sea. Take a storm, add in the boat and crew capabilities, and you don’t even need ghost pirates or dire piranha. But even a smooth sea and steady breeze can affect a party’s decision to deliver the king’s message or investigate the weird tower that’s not on the map.

Climate Change

The region’s climate is going to drive the major weather patterns, so it’s challenging to have a single weather table that contains every part of most worlds in the right measure. The frigid gales of the Kohút Mountains in the deep north are not the same as the bone-cleaning siroccos on the Mek’Madius Plateau in Timaeus. It’s likewise more believable to have a blizzard in one and scorching sun in the other. So you’d ideally have a table for each major clime and perhaps one for whatever seasons affect the area. This can lead to a lot of complexity, so keeping things simple while still delivering interesting or actionable information can be challenging.

Hex Flowers

This has been a popular alternative to the standard table with several contributors bringing a lot of thought to the structure and use. One of the more easily approachable options is the one with 19 hexes. For a more detailed explanation of the structure and many other uses, see Goblin’s Henchman. For this example, we’re going to use a d8. You can start anywhere you like, but subsequent rolls are from the last spot you were at, one step in the direction noted on the hex legend.


Instructions. Start in the space you want or roll a d20 and count from the top (or bottom). Choose a time interval for when you’re going to roll. It can be static, like every day, or you can choose times when the weather might be important to roll in the morning, then again in the afternoon. Roll 1d8 and refer to the legend hex, making note of the directions on the hex flower when you get to the edge. Most of the time you can just wrap around, but there are some hexes with lines directing you where to go. The direction indicated by the roll is also the direction of the wind during this period. Specific to the Serpent Lake Valley, the winds are more likely to go north or south, thus the numbers are weighted in those directions. Also roll 1d8 for the winds and refer to the table. Stormy weather amps up the wind force as noted. The visual weather depictions in many hexes are intentionally vague. For instance, it’s unlikely to be violently stormy for an entire day in the Valley, so you can decide when the storm hits and how long it lasts (some extra rolling here is appropriate if you want a more random result). Roll 1d10 for the relative temperature, take note of various combinations, and you’re set.

See the colored arrows for examples of what happens when crossing out of the structure.

d8 Wind
1 Calm
2-4 Light Breeze
5-7 Strong Wind
8 Heavy Gale


1d10 Temperature
1 Much cooler than normal
2-3 Cooler than normal
4-7 Average temperature
8-9 Warmer than normal
10 Much warmer than normal

If the weather is stormy, add 3 to the wind roll.

If the wind is calm and the temperature roll is 1 or 2, fog develops either before dawn and lasts the morning, or in the late afternoon, remaining long into the night.

Wind Effects on Sailing

Calm Winds: ships relying on sail have a speed of 0.

Light winds in direction of travel: normal sailing speed.

Light winds opposite direction of travel: half speed as the ship must tack into wind.

Strong winds in direction of travel: double sailing speed.

Strong winds opposite direction of travel: travel at one quarter speed as the ship must tack into wind.

Heavy gale in direction of travel: Speed is doubled, but the captain must succeed on DC 10 Intelligence (Water Vessels) ability check or the ship takes 4d10 damage to the sails component (if using 5e rules) or reduce speed by half until 3d6 hours of repairs can be made (a second failure before repairs reduces the ship’s speed to 0 until 6d6 hours of repairs can be made).

Heavy gale opposite direction of travel: Speed is 0 and captain must succeed on DC 10 Intelligence (Water Vessels) ability check or the ship takes 4d10 damage to the sails component (if using 5e rules) or reduce speed by half until 3d6 hours of repairs can be made (a second failure before repairs reduces the ship’s speed to 0 until 6d6 hours of repairs can be made).

Wind Effects on Rowing

Due to the effect of wind on the sea state, ships relying on rowing travel at half speed during a heavy gale, regardless of direction.

Wind Effects on Combat

On a wind roll of 6 or higher, ranged weapon attacks are at disadvantage. On a wind roll of 8, ranged weapon attacks beyond the weapon’s normal range automatically miss.

Sea State

With a wind roll of 7 or 8, the ship’s deck is heaving so much, all Dexterity ability checks and saving throws are made at disadvantage.

Storm Effects

During a storm, visibility is reduced to 100 to 300 feet, all Wisdom (Perception) checks are made at disadvantage, all ranged attacks are at disadvantage, and there’s a 1 in 1,000 chance of being struck by lightning sometime during the storm, taking 3d10 lightning damage on a failed DC 15 Dexterity saving throw or half as much on a success.

Fog Effects

Visibility is reduced to 100 feet and Wisdom (Perception) checks relying on sight are at disadvantage.

Be sure to check out part one of this series: The Old Polyhedron and the SeaGet in the comments or join our Discord to connect with Tim and give your feedback!

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Shopping Cart
Scroll to Top