Croatia pollen forecast
Current pollen levels and a 4-day forecast for 21 allergens across 6 Croatian regions. Follow the allergy forecast for Zagreb, Split, Rijeka, Osijek, Pula and other cities. Measurements are updated every hour.
Current forecast by region
Regions are sorted by current pollen level - the most affected at the top. Click for the 4-day forecast.
Continental Croatia
Zagreb, Varaždin, Čakovec
Dalmatia
Split, Zadar, Šibenik
Istria & Kvarner
Pula, Rovinj, Poreč
Slavonia
Osijek, Slavonski Brod, Vinkovci
Littoral Croatia
Rijeka, Crikvenica, Senj
Highland Croatia
Karlovac, Ogulin, Delnice
Forecast by city
A dedicated pollen forecast for cities with an NZJZ Štampar monitoring station. Today's pollen levels and a 4-day forecast per city.
Allergy season in Croatia 2026
Croatia's pollen season runs from January (hazel) to October (ragweed). An overview of the main seasonal periods:
Early season (winter)
January - FebruaryHazel and alder (Corylus, Alnus) are the first allergens of the year. Mild winter days can trigger flowering as early as late December. Mediterranean regions also see cypress.
Spring peak (trees)
March - AprilBirch, oak and ash are the strongest spring allergens. Birch pollen counts regularly exceed 100 grains/m³ in continental Croatia. The Mediterranean profile adds holm oak and cypress.
Early summer (grasses + olive)
May - JuneGrasses (Poaceae) enter their season and last into July. Mediterranean regions hit the peak of the olive season (Olea europaea), with counts above 200 grains/m³.
Late summer (weeds)
July - SeptemberMugwort (Artemisia) and nettle (Urtica) flower through the summer. In Slavonia and continental Croatia the ragweed season begins - the worst allergen of late summer.
Ragweed peak
September - OctoberRagweed reaches its maximum in late August and early September. In Slavonski Brod, Osijek and Vinkovci, counts regularly exceed 50 grains/m³ - double the threshold for the "very high" level.
Regional differences in the pollen forecast
The pollen forecast varies significantly across Croatia's regions because of differing climate and vegetation. Continental Croatia and Slavonia are dominated by birch, oak, grasses and ragweed (worst in Slavonia). Mediterranean Dalmatia, Istria and Kvarner have olive, cypress and holm oak - a different seasonal profile. Highland Croatia has milder levels and a later season because of its mountain climate, which makes it a popular summer destination for allergy sufferers.
Frequently asked questions - pollen forecast
What is a pollen forecast and how reliable is it?
A pollen forecast shows the expected pollen concentrations for the coming days. alergija.hr uses a two-tier data source: primarily the NZJZ "Dr. Andrija Štampar" Hirst-trap network with 25 monitoring stations across Croatia (real measurements), and as a fallback the Copernicus CAMS atmospheric model (an estimate on a ~40 km grid). The forecast is reliable 24-48 hours ahead; uncertainty grows over longer periods.
When is the pollen season worst in Croatia?
The worst months depend on the region and your sensitivity. In general, April (birch) and late August to September (ragweed) are the national peaks for most allergy sufferers. In Dalmatia the worst are May and June (olive). The season as a whole runs from February to October.
How does the pollen forecast differ across Croatia's regions?
Continental Croatia and Slavonia are dominated by birch, grasses, oak and ragweed. Dalmatia, Istria and Kvarner have a Mediterranean profile - olive, cypress, holm oak and pellitory. Highland Croatia (Gorski kotar, Lika) has milder levels and a later season because of its mountain climate.
Can I get email alerts when pollen exceeds a threshold?
Yes. Register on alergija.hr and, in your profile, choose the allergens and threshold (1-5) you are sensitive to. Each day the system checks the levels and sends an email alert when pollen exceeds your threshold. Alerts are sent once a day per allergen to avoid spam.
What do the 1-5 levels in the pollen forecast mean?
The 1-5 scale follows the WHO and EAACI classification: 1 = Low (minimal concentration, symptoms rare), 2 = Moderate (mild symptoms possible), 3 = High (symptoms likely in sensitive people), 4 = Very High (strong symptoms, asthma flare-ups), 5 = Extreme (avoid spending time outdoors).
Which data sources does the alergija.hr pollen forecast use?
Primary: NZJZ "Dr. Andrija Štampar" - the national coordinator of pollen monitoring, which aggregates measurements from 25 local public-health institutes (ZJZ). Štampar uses Hirst-trap volumetric samplers for real measurements. Fallback: Open-Meteo Copernicus CAMS - an atmospheric model that uses satellite and weather data. The two sources cover 21 allergens (Štampar) and 6 allergens (CAMS) respectively.
Data sources
Primary source: NZJZ "Dr. Andrija Štampar" - the national coordinator of pollen monitoring, which aggregates Hirst-trap measurements from 25 local public-health institutes (ZJZ). Covers 21 allergens.
Fallback: Open-Meteo Copernicus CAMS - an atmospheric model (~40 km grid). Covers 6 allergens (alder, birch, grasses, mugwort, ragweed, olive).