Yes there are triggers for almost everyone and it sounds like work is a trigger for you. The stress of work can trigger one like nothing. I have several triggers, enviromental is one. I get the kind that really don't get any warnin. but yes that can be.
I have been dealing with migraines for 26 years.

I have had migraines for 36 years! ( I am only 39!!). Never been able to figure out what trigger them- I am guarenteed to get one or two hormonal ones per month. Otherwise- all the rest are a crap shoot!

I do have alot of triggers to. I have things like repedative loud sounds, strong smells, bright light like the sun light off of the snow. And heat is a big trigger for me. But the biggest trigger is stress. I don't know of anyone who gets migraines that doesn't have triggers. It is just trying to figure out what they are and trying to avoid them. And that can be the hardest part. I wish you all the luck in the world with figuring out your triggers.

Yep, I have quite a few triggers, but it's not consistent. Lots of smells trigger me, but not always...hamburger cooking, perfumes, fragranced lotions, coffee. (Sweet smells do not trigger me, like cake baking.) Hormones always trigger it like clockwork! Weather pattern changes usually trigger, but not always. I think I do much better during warm weather than I do in winter. Who knows!

Hope you figure yours out! Could yours have something to do with the lighting? Stress?

I have a couple of things that can trigger my migraines and stress is one of them. You can be dealing with too much stress at work especially if they are only happening at work. There could be something in your office. There are times that the weather can cause it for me especially if we are going to have a really big storm. I am also allergic to artificial sweetners and red grapes which includes red wine. Just be mindful of what is around you when you get one and document it.

Heat
stress
cig smoke

The main thing that triggers my migraines is sound and sunlight. If my fiance whistles it cuts right through me. But I also have what I call my cycle of headaches, because of brain surgery for epilepsy. I have an average of 10 to 14 days a month of migrains. Some are copable but there are times when they have lasted as long as a week straight. That is when I go to bed with additional things covering my windows, my door shut and no sound within hearing distance. Good luck everyone. Oh and the only thing that can evens comes close to helping mine is Imitrex.

I know stress is a big factor..Also I have noticed some sounds seem to bring it on.

Heh, I didn't put sound on my list.. and I should have - cause my ears pick up weird electrical frequencies that are extremely unpleasant.

Anyway...list:
http://dailystrength.org/groups/migraine-411/discussions/messages/2970928

When you're at work and you feel the head ache coming, notice the time of day and your surroundings.

Do you work on the computer too much, have florescent lighting, any strange noises, loud talking, has your head been in the same position, are you hungry, is someone wearing perfume?? It could be anything!!

Start to write things down. This is what I did, and eventually I saw a pattern and learned some of my triggers.
Good luck!