I've written before about weather, hunting, and foraging in the wilderness, but I didn't really talk about miscellaneous travel woes: stumbling into poison ivy, thickets, bug infestations, tainted water sources, and the like. I've thought about it and decided I like the standard 2d6 reaction roll to determine the quality of travel: at the beginning of the journey, and again each time the party enters a new kind of terrain or after one week of travel in any terrain, roll the dice. On a result of 6-8, the journey is average. Describe flora, fauna, and other conditions, as appropriate for the terrain and abundance of life. If the result is less than 6, things take a turn for the worse, with a 2 representing something that can cause actual damage (usually 1 point/day unless steps are taken to counteract.) Stuff that is merely unpleasant but not damaging triggers morale rolls in hirelings or henchmen and can give a 1-point penalty on relevant actions, plus it interferes with things like refreshing spells. Not all of these ill effects are automatic; if the GM says "you see some large ant hills", there may only be an unpleasant effect if the party disturbs the ants or lingers in the area, while a tainted water source will only affect people who drink it.
On a result of 9+, the party has good luck during the journey, finding an easy source of food or water or some other resource. On a 12, the resource can counteract penalties or improve morale, if used properly. The trick is: the GM describes both good and bad events in mostly the same way: "There's a small spring a short ways away" might mean clean water, tainted water, poisoned water, or medicinal water. The players have to figure out which is which. Similarly, "thick brush up ahead" might be edible berries or poison ivy.
I'm debating whether an avalanche or mudslide should count as a terrain effect or a weather effect.
These dice can be rolled on the Quickie Dice Map for more detail. The lowest of the two dice can be used to determine what the party discovers (1= water, 2= food, 3-4= wildlife, 5= food, 6= water.) The position of the highest of the two d6s can provide other details.