Bellingham Allergy Seasons

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General Overview of Allergy Seasons in Bellingham and Whatcom County Washington

In our area of Northwest Washington State, the pollen season starts in late January to early February with the appearance of cedar and juniper pollens. Soon thereafter, alder and birch pollen and other tree pollens such as cottonwood, oak and maple begin to appear. Alder and birch and related pollens occur in high concentrations and are generally the most allergenic pollens in our area in the spring time. They peak in March - April.  Cedar and juniper pollen are usually less important as they are heavier pollens that do not tend to drift very far from their source. However, in some individuals these pollens can be clinically important. Tree pollens tend to decrease in concentrations in late April and early May.

Grass pollens begin to show up in the counter around mid May when tall grass starts to appear, and peak in June. They persist through mid to late July. Grass season is probably the most significant pollen season in our area which is known for high concentrations of grass pollen. This pollen is very allergenic and causes significant allergic symptoms and disruption of quality of life in many Whatcom County residents. The peak in grass pollen concentration  in June coincides with the showing of the cottonwood "fluffs" which are the seeds from the cottonwood trees. These "fluffs" are not the cause of allergy symptoms during this time of year.

Weed pollens are generally less important for allergy sufferers than tree and grass pollens in our area. They begin to show in June and July and persist through late summer. We do not have the significant ragweed problem here that occurs in the Midwest and East Coast in the fall time.

Mold spores may be present all year but generally are highest in concentration in summer and fall time.

Allergy seasons are not over with the disappearance of pollens in the air outside, as dust mites in our homes are most problematic for allergic individuals in the fall time. We close up our windows and spend more time indoors and dust mite populations increase because of the increase in indoor humidity. For many allergy sufferers, symptoms in the fall time can be almost as bad as in those occurring in the grass or tree pollen season. However, symptoms may vary for some as the "histamine"  reactions of sneezing and itching common in the spring and summer may be less important than nasal congestion, sinus headache, sinus infections and worsening of asthma in the fall time.

For those with asthma and sinus infections, viral upper respiratory infections are important triggers for worsening symptoms. These begin in our school children within the first few weeks of school in September and soon thereafter parents and other adults will begin to experience problems. There is a peak in asthma hospitalizations in children in the fall time due to viral induced asthma exacerbations. Thus, two important triggers occur in the fall time for many with asthma and allergies in our area; dust mites and viral upper respiratory infections.

Click on Pollen Counts for pollen and mold counts in our area.

Check out  Bellingham-Whatcom County Asthma and Allergy  for more information on asthma and allergies in our area.


William Anderson MD

Board Certified    *    Allergy-Immunology     *     Pediatrics and Adults

Asthma & Allergy Center of Whatcom County

2075 Barkley Blvd. Ste. 220   *    Bellingham Washington 98226