I have seasonal allergieis and asthma and I'm jut wondering if I can go outside?

Yes. The goal of management of allergic disease is that the patient should be able to do whatever they want. See an allergist, find out what you are allergic to and develop a treatment plan that may include antihistamines, nasal sprays and allergy vaccine therapy.
A few ideas. First, are you on medication? You should be taking an oral or nasal spray antihistamine &/or a nasal steroid steroid for allergic rhinitis, perhaps drops for your eyes. For asthma you should be taking a controller medication like an inhaled steroid or singuliair & a rescue inhaler. Pollen counts are lowest in early morning before the dew rises & highest on hot, sunny, windy afternoons.
Yes... If your asthma is under proper control, you should be able to be outside most days. When the news reports poor air quality either due to high ozone or high pollen counts, then you should stay in as much as possible. See your doctor if your symptoms are poorly controlled.