My (inherited) hayfever is absolutely abysmal today - and largely what brought me to this thread! I use a powerful nasal spray & tablets on prescription - unfortunately they are not working today because my symptoms are so bad, and this happens once or twice a year. "Normal" lawns don't affect me, but almost all other plants and types of garden/park seem to. Hot weather with a bit of haze is always worst, plus a light breeze... as is present today in southern England. Oddly enough, full sunshine isn't the worst thing for me, either - it's when I'm in the shade or just coming indoors. Heavy rain - summer storms - will generally be fantastically helpful. Unfortunately, my type of hayfever is also sometimes very intermittent - one hour it is really bad, and the next I have no symptoms. I can be sitting or standing in roughly the same place without the weather changing or any other environmental differences, and bang! Sneeze after sneeze. It's mainly sneezing and a bunged-up nose.
The best trick is using "Hay Max" or conventional vaseline around the inside of one's nose. You will still sneeze, so take care to avoid bogies getting stuck in the front of your nose.
As for itchy eyes, I do get that sometimes. Sunglasses (even wraparound safety specs) do not help in the slightest, so I just avoid grass and crops and try to only touch my eyes when my hands are really clean.
One good friend of mine used to get hayfever all year round and now has been prescribed tablets and sprays after visiting her GP as I recommended... however she now cannot survive without them - indeed, she often has to borrow my tablets (same drug, don't worry) if she is out and about (unhelpfully for her, she is the most forgetful person alive). My dad, from whom I inherited all this nonsense, is much better than he used to be - just as he gets older, really. Loratadine works for him when he occasionally needs it.
Sprays mentioned above: Mometasone Furoate.
Tablets mentioned above: Cetirizine Hydrochloride.
And no, I do not use those whilst carrying out any task where my reaction time needs to be spot on, as per medical advice.