Your ITV Wales Pollen Forecast

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Local Pollen information for Wales

The grass pollen season for Wales can vary quite a lot over a short distance. Although generally it can be severe in the south and towards the Welsh-English border, elsewhere Wales typically experiences a mild grass pollen.

Lower Pollen Count AreasThe wind direction in the UK is predominantly southwesterly and therefore coastal areas are less susceptible high pollen levels.

Snowdonia National Park, the Cambrian Mountains, and moor land areas across central Wales, upland areas of the Brecon Beacons and Black Mountains all typically experience a mild grass pollen season. This is mainly because upland grasses produce less pollen.

High Pollen Count AreasThe growing seasons can be long especially in the south. From Pembroke in the west to Cardiff in the east and up to 40 miles inland, the grass pollen count can be very high in June and July.

Away from the coast, any valleys with grassy meadows and agricultural lowland areas on the border (eg. Wrexham, eastern Powys) can also have very high grass pollen counts.

The Pollen Season

Running from March to the end of September, the pollen season is split into three main categories.

  • Tree Pollen - from late March to mid-May.

  • Grass Pollen - from mid-May to July

  • Weed Pollen - from the end of June to September

Pollen Calendar Credit: The Met Office

Pollen is a very fine powder produced by the male parts of trees, flowers, grasses, and weeds to fertilize other plants of the same species. Many people have an adverse immune response when they breathe in pollen.

The immune system normally defends the body against harmful invaders, such as viruses and bacteria, to ward off illnesses.

Some peoples immune system mistakenly identify harmless pollen as a threat to the body and tries to fight it by releasing a chemical. We call this an allergic reaction, which can lead to a number of irritating symptoms such as

  • sneezing

  • stuffy nose

  • watery eyes

The Pollen Count

A pollen count is generated by measuring the number of pollen grains in a given volume of air, using a pollen trap.

What effect does time of day and weather have on pollen count?

Pollen counts tend to be higher in the early morning and late evening, although they can sometimes be high all day long.

If the grass is damp, the pollen peak will be later in the morning because the water evaporates before the pollen is released.

Some grasses release their pollen in the afternoon. Pollen rises in the air during the day and then descends at night, as the air cools.

In rural areas, the evening peak tends to occur between 6pm and 9pm but in the city, where the air stays warmer for longer, the pollen descends later and levels tend to peak between 9pm and midnight or even later, which is why you may wake up sneezing in the night.

Sunny days favour higher pollen counts and rain tends to wash the pollen away. On a cloudy day, pollen builds up only to be released on the next sunny day.

Pollen transported by bees Credit: ITV/MET OFFICE