So do I Maniac! And I asked the question...ha ha. It has been humid here with the monsoonal moisture lately. I think that is what made me question it.

With everything - practically - being computerized or electronic in some way or another I don't think you'll have a problem as long as it is away from the window in case of rain. Washers and dryers, stoves, microwaves, irons, the list is endless, of products we use that are subjected to higher humidity that what your machine will be exposed to sitting in a room with a window open.

be extra careful with any computer near a window...open or closed....if you live next to a highway or airport....certain equipment in planes ...and some equipment installed for the purpose of grabbing data while driving by homes (ie. identity theft) can damage sewing machine computer parts.

The dampness at night would be of concern to me.

My mother thought night air could kill a person, let alone a computerized machine. While I love my bedroom window open at night (sorry, Ma), I wouldn't leave the window open around a machine. There is so much night dew.

My sewing room windows in my old sewing room were open pretty much 24/7 unless it was a really hard slanting rain. Never had the least bit of trouble with my machine, and it was set up (in a table) directly in front of the main window. My PC is still in that same room, not one lick of trouble there either. I'm a very early riser and often are on the machine by 3 or 4 AM on a weekend - never seen dew on my machine, or on anything else indoors, not even when we leave the big back slider open all night, which we often do. So it really doesn't seem to be a concern where I live.

If excessive humidity is that troubling to computerized machines, how does anybody in a place like like FL or HI sew??

I would be afraid it would rain overnight.

I posed this question to my husband, who has a lot of mechanical experience. He says most computers are so well built you can completely submerge them and they'll be fine - as long as they do not have any electrical power! The problem comes when you have water and electricity mixing. He said the scenario posed here - condensation forming on/inside the machine - could be possible if you live in a very humid climate, or possibly near the ocean with fog coming in at night. But you would know it, because the condensation would be on everything; the sewing machine; the table the machine sits on; the window sill, etc. He added that it would be highly unlikely and he thinks it's not worth bothering yourself over.

I think I would be more worried about cut fabric swelling up or stored fabric absorbing moisture and maybe getting a little mildew-y than about my machine. I never thought about my machine, except to cover it from the sun and from dust. Hmmmmmm