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Long, hot days are great for outdoor activities, but pollen can threaten to keep you indoors if you have pollen allergies and allergic asthma. They may leave you longing for a rain shower to wash the pollen away. But rain causes plant growth, producing more pollen, right? So is rain good for those with allergies or not?

The Good News About Rain and Pollen

Did you know pollen counts may actually be higher when it’s dry? You would expect rain to make plants grow, producing more pollen. So a dry spell would mean less pollen, right? Not really.

During dry seasons, trees can actually release more pollen.1 There is less moisture in the air to weigh down the pollen grains when the wind blows. This helps more pollen travel farther and more easily.

Light, steady rain showers can wash the pollen away, keeping it from flying through the air. The humidity that follows helps keep pollen down too. Rain can have a welcome benefit for those with pollen allergies.

The Not-So-Good News About Rain and Pollen

Overall, rain is good if you have pollen allergies. But rain can cause issues for those with allergies to grass, weeds, dust and mold.

When it rains when grass and weed pollen is high, drops can hit the ground and break up clumps of pollen into smaller particles. They then quickly disperse, causing a sudden increase in allergy and allergic asthma symptoms during the rain shower. This tends to happen more during sudden, heavy downpours.

If you’re in a rainy and humid season, mold and dust mite counts can climb. Mold thrives in damp conditions. Remove leaves before they can become a problem. Lower your indoor humidity to keep mold at bay indoors.

Dust mites can also multiply in humid conditions. If the rain is keeping you indoors, take steps to control your indoor allergens.

Watch the Weather and Seek Allergy Treatment

Rain can be a good thing for pollen allergies. But you can have too much of a good thing. Next time the showers rain down, be grateful for the temporary relief. If the rains keep pouring down, watch out for a spike in mold, dust, and weed and grass pollen soon after.

You can manage your allergies and allergic asthma by visiting a board-certified allergist to help you manage your symptoms and by tracking the weather and pollen on these sites:

Accuweather/AAFA personalized respiratory forecast – Visit for a personalized asthma forecast for your area. Enter your location. Then from the Personalized Forecasts drop-down menu, choose Respiratory. The Accuweather/AAFA forecast will show asthma alerts along with your forecast. The page also includes tips from AAFA on managing weather-related asthma issues.

National Allergy Bureau – Sign up to receive email alerts or download the app from the AAAAI to alert you of your area’s pollen counts.

Many treatments are available to help you manage your pollen allergies, no matter what the weather does. AAFA’s annual Spring Allergy Capitals™ report provides insights into cities where people are most affected by spring allergies. Download the report to see where your city ranks.

Medical Review July 2017, updated May 2018

It is important to stay up-to-date on news about asthma and allergies. By joining our community and following our blog, you will receive ongoing information about managing your health. Our community also provides an opportunity to connect with other people who manage asthma and allergies.


1. G. G. Franchi, B. Piotto, M. Nepi, C. C. Baskin, J. M. Baskin, E. Pacini; Pollen and seed desiccation tolerance in relation to degree of developmental arrest, dispersal, and survival. J Exp Bot 2011; 62 (15): 5267-5281. doi: 10.1093/jxb/err154

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