Grass pollen is the most important cause of hay fever in the Netherlands. Approximately two million Dutch people suffer from a grass pollen allergy. The season extends from May to August, but the peak differs by region and by year. In this article you will learn when to expect the most grass pollen in your part of the country.

In brief: the grass pollen season runs from May to August. The worst period is late May to mid-July, with June as the peak month. In the south the season starts 1--2 weeks earlier. At the coast, concentrations are lower than inland.

When does the grass pollen season start?

The first grass pollen typically appears in the Netherlands in May. In warm years this can be as early as mid-April -- in 2024 the grass pollen season was classified as "very early". The start depends on temperature and rainfall in spring: warmth accelerates grass growth, while a wet and cold spring delays the season.

When is the peak?

The grass pollen peak generally falls late May to mid-July, with June as the worst month for most hay fever sufferers. The peak period lasts on average four to six weeks. During these weeks, concentrations can reach very high levels, especially on warm, dry and windy days.

After the peak, concentrations gradually decline, but grass pollen remains detectable into August. With sufficient rain in the summer, a second, smaller flowering period can occur when grasses regrow.

Regional differences in the Netherlands

Coast (Zeeland, South & North Holland)

Lower grass pollen levels. The sea breeze dilutes concentrations and carries pollen inland. Beach days with a westerly wind bring relief.

Countryside (Gelderland, Overijssel, Drenthe)

Highest grass pollen levels. Extensive meadows and hayfields produce large quantities of pollen. The Veluwe and the Green Heart are hotspots.

Cities (Amsterdam, Rotterdam, Utrecht)

Variable concentrations. Parks produce pollen locally, but built-up areas limit dispersal. The season sometimes starts earlier due to the urban heat effect.

Southern Netherlands (Brabant, Limburg)

The season starts 1--2 weeks earlier than in the north as spring temperatures rise more quickly. The peak can fall as early as late May.

The impact of weather on grass pollen

Heat & drought

Grasses flower faster and release more pollen. Concentrations are highest on warm days with a light breeze.

Rain

Washes pollen out of the air temporarily. After a rain shower, pollen pressure is briefly lower -- the best time to go outside.

Wind

Spreads pollen over large distances. With a northerly wind, concentrations in the south are lower, and vice versa.

Thunderstorms

Can rupture grass pollen into smaller particles that penetrate deeper into the lungs. Read more about thunderstorm asthma.

Tips during the grass pollen peak

  • Check the live pollen map every morning for your province.
  • Schedule intensive outdoor activities early in the morning (before 6:00) or after 20:00 -- pollen concentrations are lowest then.
  • Wear sunglasses outdoors to reduce pollen entering your eyes.
  • Shower and wash your hair when you get home to remove pollen.
  • Use an antihistamine or nasal spray daily -- preferably starting two weeks before the season. See our antihistamine comparison.