The BBC keep a daily pollen forecast. I find that what's happening locally is a lot more important. I can be fine one minute, then walk past a particularly bad tree and not stop shaking for a quarter hour. Thomas Ogren says turn back the pollen clock (New Scientist Opinion section): The rise of hayfever is due to the replacement in cities of elm (which are mixed male/female and were wiped out by Dutch Elm Disease) with exclusively male trees (females litter seedpods) which produce a lot of pollen. Hence hay fever. Don't take this idea too seriously though. When The Times covered male trees and allergies they quoted an allergy professor at UCL. Paraphrasing: The rise in hay fever cases is occurring in June/July, which is when grass pollinates. Trees pollinate from February to April.