cRPG is a popular modification for Mount & Blade: Warband. It adds persistent multiplayer character stats, hundreds of unique items, an online campaign, clans, duel ladder, a co-op game mode and a few more things.
Here we see two of the various dynamic weather conditions that can occur in both the Strategus and regular game mode servers.
Visible here are fog and rain, both of which affect movement speed, weapon proficiency, and ranged projectiles speed/damage.
Other possible weather conditions include sandstorms and snow/blizzards.
Current weather can be seen on the cRPG website.