No mystery there, water intrusion problem would be from snow melting off my boots and puddling on the plastic floor mats. I hit my boots together before getting in, but I can't eliminate it completely. It causes less problems for me since I started keeping desiccant packs around. I don't like it, but this source alone has never been bad enough to be a danger to drive with, even when it's -20C.

I have the same style of manual controls as @pavelvoivoda but mine doesn't have the "use with" diagram. Probably a 99+ thing. I never used recirculate but I'll try turning those vents on immediately instead of waiting for the engine to heat up.