A idea I came up with a while back but to bring little realistic... and more depth... from snow, to rain, even heat waves.

"It begins to rain"
First time playing on here I thought "Can i use the rain to drink?"
Most the time the weather affects very little maybe a spell here or there....
But it could do so much more.

When raining and your in dire need of something to drink? Fill a container with rain water?(Food)

That warrior in heavy armor full plate trudging through the muddy terrian would have his movement decreased wouldn't you think?(Heavy Armor)

Water has many affects on the natural world.. Including shaping and changing the world... Wouldn't tracks be impossible to follow through the muddy terrian?(Ranger)

Usually when it rains birds find a pirch to sit on to stay out of the rain... When most birds feathers get wet they become unable to fly till they dry off.(Arial)

Just some ideas i thought how gameplay could get more 'depth' with weather that makes you think... What do you guys think?