Since my parents and now sister are here, there is surely some psychosomatic component. I do recall having this feeling quite often as a teenager and on more recent visits home.
But the unease is less focused than that, more abstract.
By far the best description I can muster is Joan Didion's prose in The White Album, when she's detailing the effect of Santa Ana winds. I can't quote it here, though, because the book is in our bedroom, where my parents are presently sleeping.
Of course, there are very strong Santa Ana's wreaking havoc in Southern California right now. Fire all over the place.
I suppose my earlier entry about "earthquake weather" can and should be extended to include the autumn threat of firestorms.
I have a good story about the Oakland Hills fire of 1991 too.
Anyway, I'm not sure whether Santa Ana winds in the Golden State can have much effect on the mood of a person living in Tucson, but I'd be a good test subject for a study.
Oh, and the humidity is once again reading "L%" in here, though the night is much cooler than earlier this week.