I'm using my Clemence Birkin today and it's raining, not only I don't cover it with rain protections of any kind, but I don't even dry it with a dry cloth, I do when it rains a lot, but not with a light drizzle....and it's just fine!
Both clemence and togo are very sturdy and good for everyday. However, clemence can get slouchy and togo retain the shape better. The slouchy or structured look is a personal preference.
Fjord is another great everyday workhorse option. Rain or shine! It is not as heavy as it used to be and is even more structured than togo or clemence.
No worries with these. As long as a handheld bag is an everyday bag for you and not a shoulderbag, then a birkin in these leathers will work perfectly!
I use my togo and clemence birkins as everyday bags even in the rain. However, I do keep a waterproof pouch like the envirosax inside my bags just in case of heavy rains. If it's a slight drizzle, I don't even bother.