Pollen

Pollen in Minneapolis:

• Weekly pollen counts by type
• Length of pollen season by year
• Number of elevated pollen days
• Percent pollen by type and species

Exposure to pollen can cause symptoms of seasonal allergic rhinitis (also known as hay fever) and asthma. Most of the pollen that can trigger allergies and asthma comes from trees, weeds, and grasses. Pollen grains from these plants are small, light and dry and easily distributed by the wind. Pollen for some species, like ragweed, can travel very long distances – up to 150 miles.

Note: Due to limitations in collection resources and impacts of the COVID pandemic, there is very limited pollen data collected for 2021 and pollen was not collected in 2022. As of 2022, no more pollen data is being collected in Minnesota. For more information on pollen, mold and other allergens, and how to manage allergy symptoms go to National Allergy Bureau.  

There are three pollen seasons in Minnesota. As shown in the graph above, trees are the first to release pollen, typically starting in early April and ending in late-May. Grasses usually begin releasing pollen in early June and ending in July. Weeds typically begin releasing pollen in mid-June and continue until the first hard frost. Ragweed pollen, which is highly allergenic, is present from early-August through mid-October. In general, trees have highest pollen levels in and around the Twin Cities metro area, followed by weeds and grasses.

If you are allergic to a certain type of pollen, it is important to know when its season begins so you can begin taking medication in advance of the season and avoid pollen once it has begun. Knowing which pollen triggers your symptoms can help you prepare for the season to reduce your exposure and symptoms.

This chart shows the length of pollen season for each plant category from 1993-2020, with start- and end-dates in the accompanying table. There is substantial variation in the length of the pollen seasons from year-to-year because a plant’s pollen season is affected by weather patterns and climate trends. These and other factors can impact the way data are collected by a pollen monitor.

This chart shows the number of elevated pollen days by pollen type. Elevated days can show pollen severity, which may impact people with allergies more. The number of elevated tree and weed pollen days has a general upward trend, however there are also more pollen samples in later years. 

These pie charts show the different species of tree and weed pollen measured at the Minneapolis pollen monitor over the 2020 pollen season. The predominant types of tree pollen were oak, juniper/cedar, mulberry and birch and the predominant types of weed pollen were ragweed and nettle.

Note: The above data reflect pollen levels in Minneapolis. Pollen can travel in a 100 to 150 mile range.

Last updated March 2021. Content is updated when data become available.