When Is Allergy Season? Tree, Grass and Weed Pollen Through the Year

01Calendar

The allergy calendar at a glance

• Late winter to spring (February to May): tree pollen, starting with hazel and alder, then birch, plane, oak and olive in Mediterranean areas.
• Late spring and summer (May to July): grass pollen, the most common cause of hay fever.
• Late summer and autumn (August to October): weed pollen such as ragweed, mugwort and nettle, and outdoor mould spores.
• Winter and all year: house dust mites, pet dander, indoor mould and cockroaches.

Dates vary by region, altitude and weather. Pollen forecasts and local pollen counts give the most accurate picture.

02Spring

Spring allergies: tree pollen

Tree pollen is released early, sometimes in late winter during mild spells, which is why some people think they have a cold that will not go away in February or March. Birch pollen is a major trigger in northern Europe and is linked to oral allergy syndrome, an itchy mouth after eating raw apples, pears, peaches or hazelnuts.

In Mediterranean regions, olive and cypress pollen are important. See itchy throat and ears.

03Summer

Summer allergies: grass pollen

Grass pollen affects most people with hay fever. Counts are highest on warm, dry, windy days, in the early morning as pollen is released and in the evening as the air cools and pollen descends. Thunderstorms can break pollen grains into smaller particles and trigger asthma attacks in sensitive people.

Grass pollen season usually peaks in June in much of Europe and North America.

04Autumn

Fall allergies: weeds and mould

Ragweed is the main cause of fall allergies in North America and is spreading in parts of Europe. Mugwort, nettle and plantain also release pollen in late summer. Damp autumn weather and decaying leaves increase outdoor mould spores, and indoor mould grows when heating starts and windows are closed.

Fall allergies are often confused with colds as the school year begins. See allergies vs cold.

05Winter

Year-round and winter allergies

If symptoms continue all year or worsen in winter, indoor allergens are the likely cause: house dust mites in bedding and carpets, pets, indoor mould and cockroaches. Symptoms are often worse in the morning and in the bedroom.

See winter allergies and non-allergic rhinitis if allergy tests are negative.

06Climate

Why allergy seasons are getting longer

Warmer temperatures and higher carbon dioxide levels are making many plants flower earlier and produce more pollen. In many regions, pollen seasons now start earlier and end later than a few decades ago. Air pollution can also make pollen more allergenic and the airways more reactive.

07Symptoms

Symptoms of seasonal allergies

• Sneezing, often in bursts.
• Runny, watery nose or a blocked nose; see how to stop a runny nose.
• Itchy, red and watery eyes.
• Itchy nose, throat and ears.
• Cough and postnasal drip; see can allergies make you cough.
• Tiredness, poor sleep and difficulty concentrating.
• Worsening asthma.

08Prepare

How to prepare for your allergy season

• Start a steroid nasal spray 1 to 2 weeks before your usual season and use it every day.
• Keep non-drowsy antihistamines at hand.
• Check pollen forecasts and plan outdoor activities for lower-pollen times.
• Keep windows closed on high-pollen days, especially in the bedroom.
• Shower and change clothes after being outdoors, and dry laundry indoors.
• Wear wraparound sunglasses and put petroleum jelly around the nostrils.
• Use saline rinses to clear pollen from the nose; see neti pot sinus rinse.

09Specialist

Allergy testing and immunotherapy

Skin prick tests or blood tests identify which pollens and indoor allergens you react to, which helps you time treatment and avoidance. For people with severe symptoms despite medicines, allergen immunotherapy, given as tablets under the tongue or injections over about three years, can reduce symptoms and the need for medicines for years afterwards.

An ENT specialist also checks for problems that worsen symptoms, such as a deviated septum or nasal polyps.

11Summary

Key points to remember

• Tree pollen peaks in spring, grass in early summer, weeds and mould in autumn.
• Year-round symptoms suggest indoor allergens.
• Starting nasal sprays before the season improves control.
• Allergy tests and immunotherapy help when symptoms are severe.