I go by: If it's okay for me, it's okay for my banjo(s).    The hygrometer (?) in our kitchen shows about 35-42% [pretty much the middle of the  "normal" range] year-round, though in summer we do run a room dehumidifier in the basement.    Best for me is me is banjo on my lap .... second best is on it's stand for easy access. 

You may have just triggered the age-old stand vs. keep in the case debate. We haven't had that for, at least, weeks. Emotions can run high :-) The answer, humidity-wise, is that it depends. Really low humidity can cause fret sprouts (saw toothing) and even lost inlays. I have noticed problems starting in the 30% range. My rule of thumb is 40-60%. I use those things that absorb excess humidity and release vapor in the case. In fact, it's probably about time to order another round.

I live in hot, dry West Texas and the humidity gets down low in the summer. I've always left my banjo out on a music stand, never in the case. Of course, I don't have any little kids or big dogs to knock it over.

I've had the banjo out in hot weather, low humidity, cold weather and humid conditions. Nothing seems to bother it.

A hygrometer will answer your question. Monitor the ambient humidity while your forced air is running and when it's not running to see where the highs and lows are. You should maintain between 45% and 55% as a rough general rule. If the forced air causes it to dip below this range then you might start thinking about keeping in the case with a case humidifier. Or a room humidifier would also be an option.

I just looked up average humidity in Baltimore and I would venture to guess that you will probably be alright. Seems like the outdoor humidity averages in the 50s, 60s, and 70s. I have to make a real concerted effort to maintain appropriate humidity where I live, but our ambient humidity in the high desert often measures in the 10%-15% area.

Also, I have observed my banjos to be less susceptible to humidity changes than my guitars. But do with that info what you will.

:) :)

I burn between 4 and 6 cord of firewood every winter.That's my main heat source/2 woodstoves.
I leave my instruments in stands or in the Lazy-Boy ready to play year-round.
Everything's staying together,here.

I've known ONE banjo that reacted to humidity of changing seasons. It was a walnut Mastertone conversion neck and it would back-bow back and forth from summer to winter and back. I can't remember which season made it bow which direction. It was kept in a case but taken out and played basically every day, year round.

The only "cure" was a heat lamp and weights, which more or less took care of it, based on the owner's eye-balling of when adjustment was needed.

I have always lived in the northeast and dealt with moderately humid summers and VERY dry winters.

I spent my career working in laboratories (in paper mills) where the humidity had to be controlled year-round to 50%, because paper is SO reactive to humidity that you can't trust any tests performed on paper unless humidity (and temperature) is controlled to the international standard. Your home heating in a northeastern winter simply doesn't have the power to humidify an entire house. Portable ultrasonic humidifiers can help an enclosed room, but you have to haul water to them every day.

I humidify in winter for my GUITARS and fiddle, not my banjos.

That is a very good question and the correct answer is: it depends.

Some factors influence the decision. If you have a pre war banjo, you will be fine. The banjo already survived the war.
But you also need to check the serial number and ensure, that the production date determined by that number is ok when the wood was harvested.

The formula is of course highly vendor-dependent. If your banjo has no serial number at all, you are not lost - your fallback is carbon dating, but you need a piece of wood for that - if you disassemble the banjo, a tiny piece from the heel will do, so the surgery stays invisible.

I would ignore snarky comments on this topic ...

Mine are hanging on the wall, on string swings, year round, for years and years. Kansas has its share of climate swings. Never any problems whatsoever. In fact, when it gets super dry, and I feel fret sprout, it’s a great time to dress the fret ends.

Cases are for transporting to jams and gigs, storing spare packs of strings, and putting stickers on.

I live on the end of a peninsula that sticks out into the Gulf of Maine,so there is a source of moisture.
I have a humidity gauge on my little temp/barometer/humidity gauge nailed to the wall and it hovers right at 45% in the dead of winter.
Right now we're seeing the effects of a 3 day nor'easter with heavy wind and rain and a low barometer.
Humidity is 60% right now,but will drop to around 50% when the wind comes around from the northwest and the sun comes out.

No wonder I need a truss-rod.

mine is a cool dry weather banjo.... or it seems to be. i noticed at some festivals it sounded bound up in damp humid conditions but id it was cool and dry it would really honk ! or it could have just been my ears.