My eyes essentially explode out of their sockets while I have hayfever.
I usually get it bad from May to mid-July.
Everyone gets it at different times, since most two sufferers aren't allergic to the same pollen. You can be allergic to the pollen of any number of plants that start to be pollinated in this area.
For me, I believe it's grass pollen, since I get it bad near cut grass. That might not be true though, since grass is usually cut when it's warm and dry, which might be responsible for any number of other plants to start pollinating.
I'm on Cetirizine at the moment, which seems to be doing alright, but I've had to change to different antihistamines in the past before.