If we could bring ourselves back to a discussion of the weather for a few moments, I'd like to discuss a difficulty in presentation that I've had for ... practically ever, or at least since I began to be as granular as I am with the game.
How do you retain the sense of the time period while giving information about what the weather is like? If you want the slightest degree of verisimilitude, you can't just tell the players the exact temperature, or the dew point, or the number of millimeters of rain. How would they know these things? The thermometer hasn't been invented for most worlds, and it certainly isn't widespread in by 1650 (when my world takes place); a number of thermometers have been created by individuals, but there's no set scale yet - Fahrenheit isn't born until 1686. Oh yes, of course you can just tell the players ... but somehow this kills the romance of the situation, as does any circumstance where you incorporate too much scientific precision into a game whose time period doesn't possess it.
I have tried to express temperature in terms of its general feel: the weather is brisk, or cool, or warm or very hot. Rain can be described as light, moderate or heavy. The wind as light, blustering or strong. However, it is probable as the gentle reader considers those words, some of them have specific, measured meanings ... we know, for instance, that a 'gale-force wind' has a wind speed of 39-46 mph., or 62-74 km per hour. We can look at the Beaufort Scale and see that the wind will cause "moderately high waves with breaking crests forming spindrift, that some twings will be broken from trees, and that cars will be forced to veer on roads. Progress on foot is seriously impeded."
But what does that mean, exactly? It's defined very well for meterologists, but what precisely is the effect on player characters in the game? Can they still travel? How far? How difficult is it for them to set up camp - how long does it take? Can their tent withstand the wind or no? What about if they set it behind this pile of rocks here, or between these trees? How is combat effected? How far can an arrow be considered accurate, or how far can you still throw a hand axe? If there's debris in the air, what's the visibility? How different is it now that its autumn as opposed to spring? What would it be like if this were winter? How much food do I need to eat if I have to work in this weather? And so on and on and on.
The fact of the matter is that weather is largely ignored for RPGs and VGs because these questions are relatively unanswerable. Even today, we retain a media where staged, filmed scenes do not feature so much as a stiff breeze (which is what, exactly, on the Beaufort scale?) ... even those filmed by David Attenborough for his Planet or Life series. Cameras don't operate well, visibility spoils the clearness of shots, damaged equipment is ridiculously expensive to replace and so on. We might get a shot of a lighthouse getting slapped by wave after wave, but these things are filmed from a distance, widescreen, and not from some idiot standing on the rocks waiting for the wave to come on. At any rate, watching it filmed tells us virtually nothing about actually experiencing the event. It's just interesting.
If the players are going to experience the event, vis a vis the game, it would be nice if they could have some sense of what it meant. Unfortunately, mere descriptions are subjective and little more than window dressing. I can say the weather is brisk, but it means different things to different people and if it doesn't stop them from travelling twenty miles today, what the hell do they care? Even if it means they only travel 18 miles, so what? It's just math to them ... it has no visceral impact, and because of that it remains fluff.
Weather is not fluff. Weather kills people, weather is dangerous, weather affects everything about being outdoors. Yes, we can create some table that describes how much damage a particular weather causes (more math), but that doesn't really bring home the feeling that the sky turning grey and the winter coming has huge implications for the party's probable well-being. It doesn't often enter into their calculations for safety and so on.
Worse than the weather turning bad, however, is the weather turning for the better. Consider: we human beings are immensely effected by the prospect of finding ourselves outside on a nice day. It changes everything about our moods. It is a wonderful, terrific thing ... but in D&D, it is utterly meaningless. Again, it has zero influence over the actions of a party. They can try to appreciate the description, even roleplay up to it, but it's an empty effort and well we all know it. I can make a nice day as a DM on a whim, and well the party knows it.
So we come against the other really annoying thing about weather. There is always, always a feeling on the behalf of parties that the DM is really just fucking with us. Why is it raining? Is there any purpose to it other than fixing things the way the DM likes? If we're really running a sandbox, why is it the sun disappears so conveniently before we have to march off to Xanadu? Why is it the rain is exactly as heavy as it is? How come the mud is just this deep that my cart gets bogged into it? My, my, aren't the gods heavily invested in making sure the weather is a hazard for us personally.
Seriously, don't you feel this way in real life? How bad is it that you know the motherfucker behind the screen is doing it on purpose.
If the DM has an adventure pre-planned, even in a sandbox setting - where presumably its something that's waited in that copse of trees since the DM postulated it three years ago - can you tell that the weather was rolled randomly? Is that DM ready to run that awful, pre-ordained frozen village where there's three inches of frost on everything in the SUMMER, too? Or have we insufferably insisted that it's never summer on this particular hill, which of course goes unnoticed by the 21st level druid that manages this particular continent? Probably the latter. Rain and snow are such wonderful mood-setters, we can't give them up just because they're not in season, right?
I could really use a set of clear, precise rules on the effects of a particular temperature, or a particular intensity of precipitation, or of a particular wind speed, on a party and its doings, in such a way that when things do come together to form a nice day, it's noticeable. That would be very nice.
Eventually I'm going to figure out how to make that happen.