(1) Season - Allergens are heaviest in spring and fall
(2) Climate/Weather - Rain and dry spells can affect seasonal variation of allergens
Most weather apps online now list the hay fever burden from season to season. Following these reports can help predict the need for antihistamines and nasal sprays (the latter can now can replace the need for antihistamine tablets) to treat hay fever. These medications can obviate the need for allergy shots which were used in the past!!!