Horsham pollen forecast - today, tomorrow and the week ahead

On 25 June 2026, overall pollen levels in Horsham are high. Grass is the main contributor to airborne pollen

On 26 June 2026, pollen conditions in Horsham will be similar to today, with grass at high levels

According to the five-day outlook, grass and cypress pollen levels will increase later in the week.

On 25 June 2026, Grass is the dominant pollen source in Horsham. willow, alder, birch, hazel, and cypress are not currently active.

Horsham's pollen season opens with hazel and alder from late January, earlier than in northern UK cities due to the mild Sussex climate. Oak and ash follow through April and May, with grass peaking through June and July. The High Weald woodland contributes substantial tree pollen during spring, while surrounding West Sussex farmland and the South Downs extend grass pollen into August under the dry southeast climate.

The Horsham pollen forecast is updated four times daily. See the timestamp below for the most recent update.

Studies show that most pollen exposure (often 70–90%) comes from nearby sources, such as local trees and vegetation. A good pollen forecast therefore depends on accurately representing local vegetation. Pollen can travel long distances, but this usually matters only early in the season or during specific wind events.

Pollen data is often misunderstood. Most "pollen levels" are not real-time measurements, but forecasts.

Direct pollen measurements are typically delayed by 1-2 days because they require manual analysis. To show current conditions in Horsham, modern forecasts combine recent measurements, weather data, and information about local vegetation.

This allows us to estimate pollen levels for today and the coming days, not just report the past.

Airmine’s atmospheric monitoring platform was developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team, using satellite and Earth observation technologies to improve emissions monitoring.