Mastering the Elements: A Dynamic Weather Mechanic for Your Game
Exploring the in's and outs of creating weather for your play sessions.
The air is thick with the scent of damp earth and pine as you wander through the forest, guided by a strange pull you can’t quite explain. The trees seem to whisper as you move, their branches swaying gently in the cool evening breeze. You didn’t plan on coming this way, but something about the path feels inevitable, as though the forest itself has chosen it for you. And then, there it is—an old house, its weathered wood barely standing against the weight of time. Vines creep up its walls, and the windows are dark, save for one. From within, flashes of light spill out, casting eerie shadows across the overgrown yard. Muffled voices reach your ears, oohing and ahhing in unison, their tones laced with wonder.
Curiosity tugs at you, stronger than hesitation. You step inside, the creak of the door echoing through the dimly lit hall. As you enter the room, the shifting glow of a small sphere illuminates the faces of those gathered. They sit in hushed awe, their features flickering in and out of clarity as the orb’s magic swirls—lightning crackles, rain falls in delicate sheets, and snow drifts lazily within its glassy prison. The air is thick with power, humming with something ancient and untamed.
A hooded figure stands at the center, cradling the glowing sphere, its light casting long, wavering shadows. From the far side of the room, another figure steps forward, their hood falling back to reveal the face of a woman. Her eyes gleam with knowing intensity as she speaks, her voice low and commanding. “And that,” she says, gesturing to the orb, “is what we’re going to teach you to do tonight. Weather is more than wind and rain—it’s a force of nature, a tool, a story waiting to be told. And you, my dear friends, are about to learn how to wield it.”
Welcome in everyone, have a seat and enjoy your stay. I hope you’ve had an amazing week, and if not, keep challenging yourself. This week, we’re exploring a weather mechanic that I developed for another project I’m working on. After several variations, and formulas I’m quite happy with what I have now.
This weather mechanic uses a series of three tables, one of them being optional. In addition, two ten-sided dice, along with two six-sided dice are needed to generate a temperature, weather, such as rain, snow, clear skies, and optionally wind conditions. The result is an immersive detail and sense of condition that can be thrown easily into your game. Or even if you just need some weather for a story you’re writing.
Let’s start with the Temperature Table which uses a generic value to represent comfortable weather at a range of 50, and 0 and 100 being extremes of cold and heat. I did take a look at using a combination of both Fahrenheit and Celsius. It resulted in harder to read tables with too much information being crammed into small spaces.
I went with a system that more generically represents the temperature in hopes that the user could then convert it into their own personal data. Data containing what of what a given value feels like to them.
For example, for me personally, 50 representing ‘Comfortable’ is about 60 Fahrenheit (15 Degrees Celsius) for me. That might be warmer, or cooler for you. You are encouraged to interpret the values as you see fit.
Spring is right around 40, and you can think of 50 being right around the start of summer, with 70-80, full on summer with some uncomfortable temperatures, and 90-95 being nearly unbearable. At 95+, extreme heatwave's. On the negative side, 40 is similar to Fall, and 30 is the start of winter. 20 and below is frigid cold and can be thought of as arctic weather passing through.
Once you’ve rolled on the Temperature Table to find a season, or have a chosen season in mind, you only need to roll on that row until the season, or the climate you are in changes. For colder climates, roll on the appropriate season, i.e. Winter or Fall. Warmer climates, Spring and Summer.
You can roll to check the temperature as often you feel is needed. I tend to roll daily to get an idea of what the days weather till be like. Of course the weather can and does change through out the day. Rolling twice a day is also a good option.
Temperature Table:
How to Use the Temperature Table:
Identify the Season and roll 2d6 (two, 6-sided dice) and add the results together.
2-4: Use the LA (Low Average) column.
5-7: Use the MA (Middle Average) column.
8-10: Use the HA (High Average) column.
11-12: Use the UN (Uncommon) column and roll again to determine if it’s a low or high outlier (1-3 for low, 4-6 for high).
Pick a random number of your choosing, or use a d10 and add the result to find the exact temperature.
Example:
During summer and roll 2d6. If you roll an 11 - Uncommon, roll a single 6 sided die to find out if it’s an uncommon high, or low.
Result: 3 - We use Uncommon Low of 60-50. Optionally you can roll a d10, add the result to find the exact temperature.
d10 Result: 7. So it the temperature is 57. Notice how I added it to the lowest number and not the highest. It’s uncommonly cold, so the lower value is used.
Weather Table
This table determines the base weather type based on the current temperature. You should have the current temperature already, if you don't see the Temperature Table above or use one of your own choosing. Roll a single d10 and check the result against the d10 Roll Column under the current Temperature Range. For example, a Temperature of 56 would result in using the 40-60, Temperature Range. Next roll 2d10 (d100) and concatenate the results. For example, 6 and 2 make 62. The d100 should be check against the Intensity, Common Weather Types, Temperature Modifications column. See the table below and read the examples before trying to grasp the idea here.
Determine the Temperature Range: Use the current temperature to find the appropriate Temperature Range.
Roll a d10: This determines the base weather type and intensity for that row.
Roll 2d10 (d100): This determines the specific weather outcome based on the percentages provided.
Apply Modifiers: Some weather outcomes include modifiers (e.g., Clear Skies -5) that further drops or increases the temperature.
Key Notes:
Clear Skies Modifiers:
Cold Weather: Clear skies cause the temperature to drop further (e.g., -5).
Warm Weather: Clear skies cause the temperature to rise further (e.g., +5).
Temperature Thresholds:
Some weather outcomes (e.g., snow mixed with rain) only occur at specific temperature thresholds (e.g., a temperature 30 or higher, see 20-40 below).
Weather Table:
Example Gameplay
Scenario 1: A Frigid Winter Night:
Temperature: It’s 15.
d10 Roll: Roll a 6 (Medium Snow).
d100 Roll: Roll a 62.
20% Light Snow (1-20): No.
40% Cloudy (21-60): No.
40% Clear Skies -5 (61-100): Yes.
Result: The weather is Clear Skies with a -5 modifier to the Temperature, making it -5 points colder.
Scenario 2: A rainy Spring Morning, followed by a slightly humid afternoon.
Temperature: It’s 55
d10 Roll: Roll a 9 (Heavy Rain and Thunder).
d100 Roll: Roll a 45.
50% Heavy Rain and Thunder (1-50): Yes.
Result: The weather is Heavy Rain and Thunder for several hours, followed by clear skies.
Scenario 3: Another Summer Spent on Fire:
Temperature: It’s 95.
d10 Roll: Roll a 4 (Partly Cloudy to Heat Wave).
d100 Roll: Roll a 75.
10% Cloudy (1-10): No.
30% Partly Cloudy (11-40): No.
60% Heat Wave +3 (41-100): Yes.
Result: The weather is a Heat Wave with a +3 modifier to the Temperature making it 98.
Optional Wind Table
This table determines the wind conditions, which can be layered on top of the base weather. Roll a d6 to determine the wind intensity.
Wind is optional mainly due to the fact that certain weather conditions certainly contain wind. For exmaple when it’s snowing, wind is often blowing the snow around. If you’d like to know exactly how strong the wind is, feel free to check on the Wind Table and find out.
And that’s it for this week. I hope you’ve found this useful. It’s been a while since I’ve posted any new mechanics, my apologies if that’s something you look forward too. Spring is coming in my area and I’ve been getting out of my winter funk. I hope you all have an amazing week. Appreciate you, and please remember to take care of one another. We’re all we’ve got.