Long, hot days are great for outdoor activities, but pollen from trees, grasses, and weeds can threaten to keep you indoors if you have pollen allergies (also called “hay fever) and allergic asthma. They may leave you longing for a rain shower to wash the pollen away. But rain causes plant growth, which may result in more pollen, right? So is rain good for people with allergies or not?

The Good News About Rain and Pollen

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 people with pollen allergies.

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

During dry, hot 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. Climate change can also lead to higher temperatures, changes in precipitation, increased carbon dioxide levels, and changes in plant growth patterns. These can all contribute to longer, more intense allergy seasons.

The Not-So-Good News About Rain, Pollen, and Other Environmental Allergens

While rain can be good if you have pollen allergies, it can cause issues for people with allergies to grass, weeds, dust mites, and mold.

When it rains when grass and weed pollen counts are high, raindrops can hit the ground and break clumps of pollen into smaller particles. They can then quickly scatter into the air, causing a sudden increase in allergy and allergic asthma symptoms during the rain shower. This tends to happen more often during sudden, heavy downpours and thunderstorms.

If you’re in a rainy and humid season, mold and dust mite counts can increase. Outdoor mold thrives in damp conditions. Remove leaves before they become moldy.

Also take steps to control your indoor allergens. Lower your indoor humidity (ideally between 30 to 50%) to manage mold and dust mites inside.

Watch the Weather and Seek Allergy Treatment

Rain can be a good thing for pollen allergies. But it is possible to have too much of a good thing. Next time the showers rain down, be grateful for the temporary relief. If the rain keeps pouring down, watch out for a spike in pollen counts, mold, and dust mites soon after.

You can manage your allergies and allergic asthma by visiting a board-certified allergist. Many treatments are available to help you manage your pollen allergies, no matter what the weather does. Tracking local weather reports and pollen counts can help you too. Talk with your doctor to come up with a treatment plan that works for you.

Medical Review: July 2024 by John James, MD

References
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