Autumn Asthma: Why Your Asthma Gets Worse in Autumn — and How to Manage It

Why Is Autumn Bad for Asthma?

For many people with asthma, autumn — particularly September and October — is the most difficult time of year. Hospital admissions for severe asthma attacks peak during this period, and GPs see a significant increase in asthma consultations. This is not a coincidence. A unique combination of environmental, biological, and social factors collide in autumn to overwhelm asthma control in even well-managed individuals.

Understanding your autumn triggers is the first step to preventing an attack. The main culprits are:

• Fungal spores (particularly Alternaria) — at their annual peak from August to November
• Cold, dry air — directly irritates and constricts inflamed airways
• Back-to-school viral infections — rhinovirus (common cold) is the leading trigger for severe asthma attacks
• Rapid temperature changes — stepping from warm indoors to cold autumn air
• Thunderstorm asthma — electrical storms scatter fractured pollen grains at high concentrations
• Reduced sunlight — lower vitamin D levels may affect immune regulation and airway inflammation

Fungal Spores: The Overlooked Autumn Trigger

While most people with asthma are familiar with pollen as a spring and summer trigger, fungal spores are the dominant allergen of autumn. Moulds and fungi release microscopic spores into the air as they reproduce — and these spores can be inhaled deep into the lungs, triggering powerful immune responses in sensitised individuals.

The most clinically important autumn mould genera are:

Fungal spore counts are highest on warm, humid days following rain, particularly in areas with abundant vegetation, leaf litter, or decaying organic matter. Checking the Met Office or National Pollen and Aerobiology Research Unit (NPARU) spore forecasts can help you plan outdoor activities.

Cold and Dry Air

As temperatures drop in autumn, breathing becomes more challenging for people with asthma. Cold, dry air irritates the already-inflamed airway lining in several ways:

• Airway cooling — cold air draws heat from the airway lining, causing reflex bronchoconstriction in susceptible individuals
• Dryness — cold air has low humidity. Dry air evaporates the fluid layer protecting the airway lining, exposing it to irritants and increasing airway reactivity
• Mucus thickening — cold conditions increase viscosity of airway mucus, making it harder to clear and increasing obstruction

Practical strategies for cold air management:

• Breathe through your nose when outdoors (warms and humidifies air before it reaches the lungs)
• Wear a loose scarf over your nose and mouth in very cold weather
• Warm up gradually before outdoor exercise; avoid intense outdoor exertion on very cold days
• Use your reliever inhaler 15 minutes before outdoor exercise if cold air is a known trigger

Back-to-School Viruses

The return to school in September is one of the most significant contributors to the autumn asthma spike. Schools are efficient transmission environments for respiratory viruses — particularly rhinovirus (the common cold virus), which is the single most common trigger for acute severe asthma attacks in both children and adults.

Respiratory viral infections trigger asthma by:

• Directly infecting and damaging airway epithelial cells
• Triggering a powerful immune and inflammatory response in the airways
• Increasing airway hyper-responsiveness for up to 6 weeks after the infection has resolved
• Impairing the airway’s natural defences against allergens and other triggers

The September Asthma Spike

Research consistently shows a dramatic spike in emergency asthma admissions in the first two weeks of September in the UK — a phenomenon sometimes called “September asthma” or the “September epidemic.”

Key statistics:

• Emergency asthma admissions can increase by up to 70% in the first weeks of September compared to the summer average
• The spike is most pronounced in children aged 5–14
• The peak typically occurs in the second week of September, 1–2 weeks after school return
• The combination of viral infections, high Alternaria spore counts, and preventer adherence lapse during summer holidays is thought to drive the spike

Studies suggest many children stop using their preventer inhaler reliably over the summer holidays, leaving their airways more inflamed and reactive when school returns in September.

Weather Changes and Thunderstorm Asthma

Autumn weather in the UK is characterised by rapidly changing conditions — warm days followed by cold nights, high humidity, rain, and occasional thunderstorms. Each of these changes can stress the airways:

• Thunderstorm asthma: Electrical storms create updrafts that carry grass pollen grains to altitude, where humidity causes them to rupture into thousands of tiny fragments. These fragments — much smaller than whole pollen grains — penetrate deeper into the airways and can trigger mass asthma attacks. Thunderstorm asthma events have caused multiple simultaneous deaths in susceptible regions.
• High humidity: Promotes mould growth indoors and outdoors, increasing fungal spore counts.
• Atmospheric pressure changes: Rapid pressure drops associated with approaching weather fronts may increase asthma symptoms in some individuals.

Autumn Asthma Management Tips

Prepare for autumn well before September to minimise your risk of attacks:

Your Asthma Action Plan for Autumn

Everyone with asthma should have a written action plan from their GP detailing what to do at each stage of worsening symptoms. Your autumn action plan should include:

1. 1

   Daily maintenance (Green zone)

   Take your preventer inhaler every morning and evening as prescribed. Check fungal spore and pollen forecasts daily. Carry your reliever inhaler at all times. Continue as normal.

2. 2

   Worsening symptoms (Amber zone)

   If you are waking at night, needing your reliever more than twice per week, or symptoms are interfering with daily activity — contact your GP promptly. Do not wait for a severe attack. Your GP may temporarily increase your preventer dose or prescribe a short course of oral steroids.

3. 3

   Acute attack (Red zone)

   Reliever not working, cannot complete sentences, severe breathlessness — call 999 immediately. While waiting: sit upright, take 1 puff of Ventolin every 30–60 seconds via spacer, up to 10 puffs total.

For a comprehensive overview of asthma — causes, symptoms, diagnosis and all treatment options — see our complete asthma condition guide. [Pillar page — link to be activated on publication]