March 04, 2020

Northwest Pollen Levels Rise, But Rain Keeps it Down

It is not that our region needs another health concern, but allergy suffers can attest to another challenge:   the surge of tree pollen during the past month.  
But there is an interesting meteorological angle to be considered.

The latest forecast is for tomorrow (Thursday) to be a bad day, mainly from tree pollen.

And the report Monday from the Northwest Asthma and Allergy Center showed the dominance of Cedar/Juniper pollen, with Alder in second place.

But now to the meteorological angle.   Take a look at the pollen levels in Seattle over the past 30 days.  Up and down. Some days are very good, while others bring misery to the afflicted.

But why?

But why is this the case?  To explore the situation, I created a plot of Seattle pollen level and the precipitation at Boeing Field (see below).  

Wow.  There is a very strong correlation between precipitation and low-levels of tree pollen, with rain really suppressing the pollen level.
Local trees are putting out a lot of pollen now,  and today and most of tomorrow will be dry....thus the prediction for a high pollen level on Thursday.

But Thursday night, a front will come through with decent rain (see 3-h rain total ending 10 PM Thursday).  So expect some improvement on Friday--that is what the folks are predicting.

Some showers are expected on Saturday, but then a drying trend is forecast on Sunday and Monday.   Perhaps time to stock up on antihistamines.....if the stores have any left.


  1. Some with cottonwoods: I notice (in May) they don't just not have they "snow" they make when it rains, they just save up until the sun shines. Either way it clogs my gutters.

  2. Not pollen-related, but it looks like some of your concerns about computing capacity may be addressed:

    1. > https://[...]hp-cards[...]

      I remember getting my boss to put a keypunch in my office.

  3. So I'm wondering if we're gonna get a heat wave this march like we've been having the last few years.

  4. Cliff,

    Pollen is the worst! I'm glad to see the correlation with rain affecting pollen levels. It's why I like rain so much.

  5. Unfortunately, the pollen issue will only intensify in the future as CO2 levels rise. Twenty-thousand years ago, at 170 to 180 ppm, terrestrial plant life was close to extinction. Plants and trees are just beginning to thrive and most don't reach optimal CO2 concentrations until 750 to 1000 ppm. Great for the plant community and crop production, but tough on us

  6. Allergy-induced sneezing will be fun in the midst of the coronavirus panic! I'll be clearing grocery store aisles left and right.


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