UK pollen calendar

Three different pollens cause British hay fever. They arrive in sequence rather than all at once, so knowing which one is in season explains why you can sneeze through April and be fine in July, or the other way round.

The three pollen seasons

Tree pollen comes first. Alder and hazel can start in late February, ash and plane follow, then birch peaks through April. Birch is the strongest tree trigger in Britain. Tree season is largely over by the end of May.

Grass pollen is the big one. Around 95% of UK hay fever sufferers react to grass. It runs from mid-May to late July with a peak in June and early July, usually in two waves: the main one in June and a lighter second flowering in July.

Weed pollen is last and longest. Nettle, dock, mugwort and plantain run from June into September and in a mild autumn can persist into October.

How the season shifts north

Pollen seasons start later and finish later the further north you go. The gap between the south coast and central Scotland is roughly a fortnight, which is why a Kent hay fever sufferer can be past the worst of the grass season while Aberdeen is only just starting.

Southern England

Covers London, the South East, South West and East of England. Season runs roughly February to October.

Pollen calendar for Southern England, January to December.
Pollen	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tree pollen	Jan: none	Feb: low	Mar: active	Apr: peak	May: active	Jun: low	Jul: none	Aug: none	Sep: none	Oct: none	Nov: none	Dec: none
Grass pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: active	Jun: peak	Jul: peak	Aug: low	Sep: none	Oct: none	Nov: none	Dec: none
Weed pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: none	Jun: low	Jul: active	Aug: peak	Sep: active	Oct: low	Nov: none	Dec: none

The Midlands and Wales

Covers the East and West Midlands and Wales. Season runs roughly February to October.

Pollen calendar for The Midlands and Wales, January to December.
Pollen	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tree pollen	Jan: none	Feb: low	Mar: active	Apr: peak	May: active	Jun: low	Jul: none	Aug: none	Sep: none	Oct: none	Nov: none	Dec: none
Grass pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: low	Jun: peak	Jul: peak	Aug: active	Sep: none	Oct: none	Nov: none	Dec: none
Weed pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: none	Jun: low	Jul: active	Aug: peak	Sep: active	Oct: low	Nov: none	Dec: none

Northern England and Northern Ireland

Covers the North West, North East, Yorkshire and Northern Ireland. Season runs roughly March to October.

Pollen calendar for Northern England and Northern Ireland, January to December.
Pollen	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tree pollen	Jan: none	Feb: none	Mar: low	Apr: peak	May: peak	Jun: low	Jul: none	Aug: none	Sep: none	Oct: none	Nov: none	Dec: none
Grass pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: low	Jun: active	Jul: peak	Aug: active	Sep: low	Oct: none	Nov: none	Dec: none
Weed pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: none	Jun: none	Jul: active	Aug: peak	Sep: active	Oct: low	Nov: none	Dec: none

Scotland

Covers all five Scottish forecast regions. Season runs roughly March to October.

Pollen calendar for Scotland, January to December.
Pollen	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Tree pollen	Jan: none	Feb: none	Mar: low	Apr: active	May: peak	Jun: active	Jul: none	Aug: none	Sep: none	Oct: none	Nov: none	Dec: none
Grass pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: none	Jun: active	Jul: peak	Aug: active	Sep: low	Oct: none	Nov: none	Dec: none
Weed pollen	Jan: none	Feb: none	Mar: none	Apr: none	May: none	Jun: none	Jul: low	Aug: peak	Sep: active	Oct: low	Nov: none	Dec: none

What makes a bad pollen day

Within the season, the day-to-day count is driven by the weather. Warm, dry and breezy days lift pollen into the air and carry it a long way; heavy rain washes it out, though a thunderstorm can briefly make things worse by bursting grains into smaller, more irritating fragments. Counts are usually highest in the morning as pollen is released, dip in the middle of the day, then rise again in the early evening as air cools and pollen settles back to nose height.

Check your own area

The calendar above is the pattern. For today's actual numbers, pick your forecast region, which lists every town inside it, or browse all the areas we cover.