Buttercup is a 10 year old Shar-Pei Mix mix who is naturally well-behaved -- not an aggressive bone in his body -- and was so easy to train from Day 1. He is extremely respectful of human/canine space but does enjoy and want human interaction & affect. He is extremely affectionate & loyal but will NEVER "break the rules" even though the worst thing is saying "no."
Buttercup has always been terrified of loud sounds such as motorcycles and thunder & lightening. With age, his phobia has gotten worse to just hard rain & wind. The 4th of July Fireworks is his most dreaded day of the year (my vet even prescribed Xanax for him but I usually do not give it to him as it just seems to make him "drunk" and not calm).
WHAT IS FREAKING US OUT: As of this morning, Wednesday, October 17th, 2012 living just outside the New York City Metropolitan area in Westchester, NY Buttercup has been acting TERRIFIED all day!
Everyone has noticed it -- it is like we are in the middle of a hurricane but the whether is fine and I just checked the forecast and nothing unusual is expected. Buttercup is now "Velcro Dog", hides under the tables (he never does that --ever. Completely scared out of his whits. I actually just gave him a Xanax so he can relax for the night.
No, there have been no changes in our daily routine at all -- no vacations, no vacations plans that Butter cup may "sense." His physical health is perfectly fine aside from some mild arthritis as he just got his yearly physical.
Is there an earthquake, hurricane, tornado I do not know about? This is the only time he acts like this and it started 14 hours ago with great intensity!!
Any ideas? I believe there was a slight earthquake on the other side of the continent as there was a similar posting in Washington State.
Any ideas??

Construction, some high pitched machine noises you can't hear?
Or the phobia's have just gotten worst all of a sudden

No -- out of nowhere. We are in the suburbs, so any construction is very "clear." He freaks out if a motorcycle goes by while on our walk. His behavior is exactly like a horrible thunderstorm or Fourth of July. Completely anxious.
I did just read that there was a 4.0 earthquake in Maine that was measured down to CT. We are on the border of Connecticut (20 minutes) and the timing fits. That is the only thing I can think of except when there was an earthquake last July 2011 which I actually did feel when at work in NJ, I do not recall Buttercup having this reaction.
We have another dog, Izzy, a 10 year old female Newfoundland rescue. She has no phobias at al -- nothing bothers her. But she has been "taking care of" Buttercup since this started so that is different for her as well. In terms of the cats, one very sick now, so cannot judge by that and the young healthy cat seems to be reacting to the two giant dogs glued to me every second by being skittish. Bubba the cat is used to being my stalker.
Does help?