In Central Europe, mugwort pollen is a frequent cause of pollen allergy. Poland is one of the countries with the highest airborne concentrations of pollen of this taxon. Due to its high allergenic potential, Artemisia pollen may pose a significant threat to sensitive subjects during summer months. Plants from this genus often grow in urban and suburban areas. The aim of the study was to compare mugwort pollen seasons and concentrations of airborne pollen of these plants in 12 cities located in different regions of Poland: Bialystok, Bydgoszcz, Cracow, Lublin, Olsztyn, Opole, Piotrkow Trybunalski, Sosnowiec, Szczecin, Warsaw, Wroclaw, and Zielona Gora. The investigations were carried out with the volumetric method using a Hirst-type pollen sampler (Lanzoni or Burkard) operating on a 24-hour basis. The duration of the pollen season was determined with the 98% method. The earliest onset of the mugwort pollen season was noted in Opole (July 12th), and the latest beginning was recorded in Cracow and Sosnowiec (July 23rd). The maximum pollen concentrations were reported on August 7th and 8th in Lublin (177 grains/m3) and Wroclaw (100 grains/m3). In all the cities, peak days were recorded on the first 10 days of August. The maximum pollen concentrations in the other cities were in the range of 18–89 grains/m3. The highest annual pollen sum was recorded in Lublin (1423) and Wroclaw (1050). These values coincided with the highest pollen concentrations determined in these cities. The annual Artemisia pollen sums in 2020 did not have the highest values in comparison with other years in these cities. The average annual pollen sum in the five-year period of 2001–2005 was estimated at 2065 in Lublin and 1662 in Wroclaw. Therefore, it can be concluded that the risk of mugwort pollen allergy in the pollen season 2020 was lower than in some previous years.