In the past I’ve written that weather is an important element in tabletop gameplay, but I’ve reevaluated that position. Rather than calling it an “important game element,” I think it would be better termed as an “intermediate GM skill.” Yes, including weather in a game enhances the game’s atmosphere, and can potentially provide the players with an interesting handicap or boon. It’s a good addition to a game, but GMs already have a lot of things to keep track of. If something needs to be dropped, weather is the obvious choice. When I first started playing tabletop RPGs, I honestly didn’t notice that every adventure took place on a clear summer’s day. Weather was never mentioned, and nobody ever complained.
Given that weather is non-essential, I want it to require as little work as any mechanic can ever require. Random is good, but in this case, charts are bad. Charts require table space, or GM screen space. When they need to be rolled on, the GM will probably need to spend a few moments finding them. That’s too large a time investment. For weather, I want to roll a die, and immediately be able to interpret the die’s result.
I propose using a 1d12 roll. When play begins, a roll of 1 indicates bad weather, 2-3 indicate inconvenient weather, 4-9 indicate normal weather, 10-11 are nice weather, and 12 is great weather. Each new day out of doors, the GM rolls another 1d12. The same ranges mentioned above are used to determine how the weather changes, with the options being: much worse, slightly worse, unchanged, slightly better, or much better.
The GM determines the weather’s precise nature based on the current climate and season in the player’s location. Both of these elements should be predetermined using the game world’s map, and the campaign calendar. Within this context, the idea of “good” and “bad” weather is relative to how it helps the characters. While crossing plains or forests, rain would be at least inconvenient. In a desert, however, rain would be the best weather you could possibly ask for!
I like how this method utilizes a bell curve, without the annoyance of adding numbers together. Perhaps this weakness comes from my own poor education in math, but adding even small numbers together requires me to pause for a moment and consider. Not long, mind you, but longer than reading a single number off of a die. The system is also fairly easy to memorize: 1,2,3 are bad, anything with double digits (10, 11, 12) is good, and everything else is normal. And even though my decision to use a d12 was based on the probabilities which can be modeled with it, I take some small pleasure in coming up with a new use for the lil’ underutilized guy.
The number 12 has an amazing, underutilized synergy with dice games. But that’s a post for another day!
The best system I’ve used for weather so far is by far the simplest. Look outside. That’s your weather in-game. Weather systems tend to stick around for days or weeks at a time, it makes sense to me that the simple answer for weather in games is to use the patterns that are already easily available.
I suppose if you live somewhere like Seattle, perpetual rain might not be as fun to RP. Michigan has widely variable weather however, so it works out pretty well.
Not only that, but time plays an important role in my games which is separate from the real passage of time. Sometimes game seasons and real life seasons line up, but other times my players must struggle through the dead of winter while it’s 90 degrees outside.
This is literly much easier to do than people tend to lend itself, you just pick a place in the world geographically that your weather is based on before a session (usually 7 to 10 days for me.) And use that. Weather sites these days tend to actually record everything from heat, to moisture, to windspeed average to even snowfall in inches and you can pick anyday of the recorded year.