I can tell the weather just like that also. Since your Imitrex isn't working for you anymore, I might suggest my abortive (STADOL NASAL SPRAY), which works great if I get that kind of lead time. It isn't much good, say, if you wake up with a full-blown migraine, but it is the bomb if you can catch it up front.
Just my experience,
"The weather is here, I wish you were beautiful."