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birch catkins

When to expect birch pollen in Norway?

Marianne Amble

Hazel and alder (alnus) is flowering in Southern Norway, but the key allergen to many of us is birch. When can we expect the birch pollen season to start?

Last year, it was already here

In 2020, the birch pollen season started in early April in Southern Norway, a fairly typical onset. Northern Norway was covered by snow unusually late in Spring, and didn’t see levels peak before June. To watch the development of pollen in a typical year, take a look at our video.

2020 - first birch pollen recordings
First birch pollen recordings in Norway last year (2020). Data from pollenvarsel.no, image by iStock.

This year, we expect another two weeks before the season kicks in

birch pollen levels 07 April 2021
Estimated birch pollen levels 07 April 2021. Estimation by Airmine (see maps live in the Airmine app). Created using Mapbox.

The birch pollen spread has started in Europe, reaching Denmark and the southern tip of Sweden. No birch pollen has yet been measured in Norway.

Birch starts flowering in Southern and Central Europe, then the pollen front gradually moves to the north. When pollen levels in England, Germany and Poland are high, it typically takes 1-2 weeks before the flowering starts in Norway (and the parts of Sweden on the same latitude).

As we can see from today’s birch pollen map, we’ve still got a way to go before we reach high levels on the continent.

Colder than usual in Europe

Temperature relative to normals 7 days from 06 April 2021
Temperature relative to normals 7 days from 06 April 2021. Blue means colder than normal, red warmer. Based on weather forecasts from GFS, map by Airmine.

Weather, and notably temperature, determines when the pollen season starts. The temperature map tells us that the next week is forecasted to be colder than normal for most of Europe, including Norway. (With the exception of the arctic island group of Svalbard.)

Our best estimate is that it will take approximately another two weeks before the birch pollen season kicks off in Norway. Of course, a rise in temperature could very well move the onset earlier (and colder temperatures delay it even more).

Get your pollen forecasts in the Airmine app

A 4-day pollen forecast is now available for European locations in our Airmine app, together with pollen maps.

We are continuously working on our pollen models and will improve them over the next months. Any feedback from our readers/users regarding on how to improve the forecasting service is much appreciated!

Download the Airmine app here:

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