Weaponized Weather, a Crash Course

Christmas hit us hard. Ok, life hit us hard. My PC died and I did not have a working one until, like, a month ago (I actually still have issues, Radeon GPUs be damned). Anyway, now we’re back and we plan to write lots of bullshit this year, so brace yourselves!

The Importance of Weather in Real Life:

Just get out in the rain if you need examples.
Jokes aside, while real life is a great inspiration and all, realism is not always that good in games (unless you’re playing DayZ), so...

You better believe that this would have not been the same in a sunny day.
Der Wanderer über dem Nebelmeer, by Caspar Friedrich.

The Importance of Weather in Games:

Weather is a potential important condition with the possibility to modify and completely change behaviour for everyone by adding (big or small) temporary effects and modifiers to every creature and action subject to it. It is dynamism incarnated: creatures act radically different in the rain than in the sun, actions can be harder or easier, terrain can become dangerous or impassable.
Having a good weather table is a reliable way to bake chaos and danger in your games. It is a fundamental game-shaker in play, especially outdoor/hexcrawl play, that can (and will) force players to make interesting decisions (both long-term and short-term) to face, manipulate, discover and make use of weather (both dangerous and calm). It is an almost guaranteed way to make potential downtime (as hexcrawling can sometimes be) into a mildly eventful, potentially dangerous and definitely thrilling activity, and a surefire way to spice up action with dynamic conditions.
It is a way to make travel preparations slightly more interesting: it is an interesting factor to research before an adventure beside the destination itself:
Ok, The Halls of the Dark God are dangerous, we need to know what we’re getting into to face it, but we also need to actually reach it: so, what terrain and what weather can we expect? Do we need to bring heavy blankets because we’re getting ourselves into places known for chilling weather? What about snow boots? I like my feet above freezing temperatures, y’know.
Also, weather can be an extremely important element during actual play: like all environmental hazards, they are something to be used by and against the players, depending on how smart they are in their approach to the situation: knowing that the weather can kill your enemy for you can turn a chase into an attrition war (especially interesting if you play some hunters looking for unusual preys like dragons), knowing that the slippery slope becomes basically a deathtrap that can keep an opponent out of a fight without killing them thanks to mud is a major game changer, and so on.
Weather is a major candidate for unusual spells and esoteric effects: not only boosting its importance makes weather-changing spell actually useful and justifies their relatively high level, but having it affect spells in some way can be extremely important (for example, doubling the effect of spells that rely on cold during snowstorms).

Systemic Warfare:

Let’s get a little into details. We’re using our Dungeons and Dummies system for reference, which is getting a new coat of dirty paint as we’re re-writing stuff and preparing a nice and tidy PDF for ease of access.
If you want to convert our terrible examples in standard D&Desque terms:
-Afflictions are roughly equal to 1-2 points of damage;
-Injuries are roughly equal to 1d8-1d10 of damage;
-1 Difficulty is roughly equal to +2/-2 in 3-18 roll-unders, and +4/-4 in 3.x-esque terms;
-10 minutes is whatever the duration of your Exploration Turn is;
-4 hours is an adventuring turn in hexcrawl play;
-8 hours is the classic adventuring day.

Our examples are going to suck hard, since we have clearly no idea how to write stuff despite trying way too hard. Please make better ones in your games: look at the moon, not at our fingers pointing at it.

The sky is partaking in the Great Dance.
Pathologic 2 Concept Art.

Climatic Warfare:

2 main kinds of Weather: Good or Bad. Each lasts 8 hours, 50% chance of each.

Good Weather has no additional effect. Vaguely sunny, light rain that does not make the road more dangerous. Nice and easy.
Bad Weather is dangerous. Doing anything in Bad Weather gives +1 Difficulty to every Check, and it also prevents rest and ruins food and equipment. Also, there are various kind of Bad Weather, each with additional complications.
Here is an example table that incorporates both Good Weather and Bad Weather in it. Please note that, if that suits your taste, Good Weather can be expanded just like Bad Weather; we preferred not to do that because we simply find complications more interesting than bonuses in game, especially if they come from outside the character sheet.

MOUNTAIN
1-10: Good Weather, 11-14: Heavy Rain (+1 Difficulty to Navigation Checks, on failures the group gets stuck in mud and slippery slopes), 15-17: Snap Freeze (1 Affliction for every 4 hours of activity outside), 18-19: Strong Winds (+1 Difficulty to Foraging Checks), 20: Snow Torment (3 Afflictions for every 4 hours of activity outside, +1 Difficulty to Navigation Checks, cannot see past 30’)

Counterspelling Weather:

Equipment and abilities can counter at least some of the effects of Bad Weather.
Proper (biome-appropriate, maybe?) tents can allow rest without too many complications.
Heavy clothes reduce afflictions from cold weather by 1 (minimum 0), but maybe give worse armor maluses (for example, wearing it always makes armor malus step up by 1 category).
Goggles and baggy clothes protect from the bad effects of sandstorms, but don’t last forever.
There’s the potential for at least a few spells, like one forcing weather change or one setting some unusual, infernal weather.

IT'S RAINING BLOOOD
Raining Blood by INeedMyAngel.

Pluvium Sanguinis:
The caster sets his eyes to the middle of the sky, and follows the Unseen Veins of the Heavens with his gaze, tearing them apart with his will and unholy utterances. For the next day, the weather of the current hex (and of every hex in a 3-hex radius) becomes Good Weather: Blood Rain, as blood from unknown creatures rains down from the sky in reddish drops:
-Lights are snuffed out: the sun cannot penetrate through the wounded Heavens anymore, and every lightsource has its radius halved;
-nothing truly dies during a Blood Rain: every creature that dies comes back wrong, with 1d4 (d20/4) random mutations and full Ability Scores in d20 hours; there’s also a 5% chance that the soul receives irreparable damage, leading to permanent insanity;
-every 4 hours there is a 50% that anyone under the blood rain will receive a random spell cast upon him.
Must be cast as a Ritual. For each extra Spell Level invested into it, it lasts one more day.

Sorry this is not very good 

Life as a dumb programmer and as a starving artist hit us hard. The little spare time we had is being used to prepare the PDF of our heartbreaker (which is probably becoming a little better, in terms of both writing and organization). We are thinking about pretentious latin titles because they sound cool. Something something descend in the dark, a low fantasy game by Bad Whiskey Games.