Is hay fever worse when it rains?
Rain's effect on hay fever is more complicated than it might seem. While rainfall generally reduces pollen levels by washing it out of the air and weighing it down, rain can actually worsen symptoms in certain conditions—particularly during thunderstorms, when humidity causes pollen grains to burst open and release smaller, more allergenic particles that penetrate deeper into your airways. The timing and intensity of rain matters significantly: heavy, prolonged rain early in the morning keeps pollen counts low all day, but afternoon rain has less impact.
Key points:
- Rain typically lowers pollen counts by clearing the air and keeping pollen grounded
- Thunderstorms can trigger worse symptoms by rupturing pollen grains and releasing concentrated allergen fragments
- Increased humidity from rain creates conditions for mould spores to grow, which can also trigger allergic reactions
- Checking pollen forecasts rather than assuming rain will help is the best way to prepare for any weather
This text has been fact-checked for accuracy by medino's clinical team.