Well, I live in a tourist area, which does quite well with even winter tourism, as long as the snow flies...
So, we'd be fairly busy through until just before Christmas, the salon portion would be busy until New Years and then January would slow down a little. But the month I always found was really dead was March.
So, eventually I figured out that was a great month for me to take a vacation. LOL
I think it depends somewhat on your client base and why they're coming to you for massage. If it's more about pain relief that pampering... they'll probably try to be more regular.
Some of my clientele came from the salon (mostly tourists... a very few hair clients who would come for massage randomly)... but my regular clients were the ones I was able to "drum up" myself by talking to chiropractors and other health professionals, and leaving brochures and business cards in their office. Because they didn't have room for me in their office, they didn't mind referring to me at the salon... and it made their patients happy to have them refer them for massage. (And it helped bring more money into the salon, so they weren't going to complain... LOL)
And if you're going to have slow months... and you've been warned by the salon when those tend to be... you can always plan some kind of special promotion during those months to see if it can drum up a few new customers!