Respira
Pollen calendar for your city
Pick your city and tick your allergies to see the months your pollen is usually at its worst, what this month looks like and what comes next. For 19 cities in the UK and Ireland and 50 in the United States.
Your pollen calendar
Pollen calendar for London. Each row is a pollen type and each square a month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Grass | January: None or almost none | February: None or almost none | March: None or almost none | April: None or almost none | May: Low | June: High | July: Moderate | August: Low | September: None or almost none | October: None or almost none | November: None or almost none | December: None or almost none |
| Birch | January: None or almost none | February: None or almost none | March: Low | April: High | May: Low | June: None or almost none | July: None or almost none | August: None or almost none | September: None or almost none | October: None or almost none | November: None or almost none | December: None or almost none |
| Mugwort | January: None or almost none | February: None or almost none | March: None or almost none | April: None or almost none | May: None or almost none | June: Low | July: High | August: Low | September: None or almost none | October: None or almost none | November: None or almost none | December: None or almost none |
| Alder | January: None or almost none | February: Low | March: High | April: Moderate | May: None or almost none | June: None or almost none | July: None or almost none | August: None or almost none | September: None or almost none | October: None or almost none | November: None or almost none | December: None or almost none |
- Low
- Moderate
- High
- Very high
- None or almost none
- No data
Grass, birch, mugwort and alder: the Copernicus CAMS model (via Open-Meteo), the 2023–2025 average of the daily highs at London's coordinates. A model, not a pollen trap.
Know when yours starts
Respira shows today's level for each of your pollens where you are, a multi-day forecast and a symptom diary, and lets you know when your season begins. Free for iPhone.
How to read the calendar
Each square is the usual level of that pollen in that month, not this year's: a wet or warm spring moves the season by a few weeks. For today's level, open the city's page or the app.
In the UK and Ireland the rows come from the Copernicus CAMS model at the city's own coordinates: the 2023–2025 average of each day's high, graded with the same thresholds as the daily level. A model gets the timing right more reliably than the amount, and it usually reads lower than pollen traps at the spring peak.
In the United States the rows carry the Estimate tag. They are Respira's seasonal calendars for each region, the ones the app and the US city pages use. The Google Pollen API that feeds the app's daily US levels has no history to average, so there is no model row to show instead.
A pollen only appears where there is data for it. If the model never puts it above almost nothing in a city, it is left out: there is no season to show.
When does hay fever season start in the UK and Ireland?
Trees come first, then grass, then weeds such as mugwort. By the model's 2023–2025 average, these are the months each pollen reaches moderate or above:
- London: alder from March to April; birch in April; grass from June to July; mugwort in July.
- Dublin: birch in April; grass from June to July.
Each city's months differ a little. Pick yours in the tool above, or see every city on the UK and Ireland pollen map.
Pollen seasons across the United States
The US has no single season. Respira's regional calendars put each pollen at moderate or above in these months:
- New York (the Northeast): elm from February to April; alder from March to April; maple from March to May; juniper / cedar from March to April; birch from April to May; ash from April to May; cottonwood from April to May; oak from April to May; pine from April to June; grass from May to July; ragweed from August to October.
- Chicago (the Midwest): elm from February to April and in September; juniper / cedar from February to March; alder in March; ash from March to April; cottonwood from March to April; maple from March to May; birch from April to May; oak from April to May; pine from April to May; grass from May to August; ragweed from August to October.
- Atlanta (the Southeast): elm from January to March; ash from February to April; cottonwood from February to April; maple from February to April; oak from February to May; pine from February to May; grass from March to September; ragweed from August to October.
- Dallas (the Southwest): juniper / cedar from December to February; ash from February to April; cottonwood from February to April; elm from February to March and from September to October; maple from February to April; grass from March to September; oak from March to May; pine from March to April; ragweed from August to October.
- Seattle (the Pacific Coast): alder from January to April; birch from March to May; ash from March to April; cottonwood from March to May; elm in March; maple from March to April; juniper / cedar from March to April; grass from April to July; oak from April to May; pine from April to June.
Every other city is on the US pollen map.
Frequently asked questions
What is a pollen calendar?
A table of the months each type of pollen is usually in the air in a place. It tells you when your season starts and ends, not how much pollen there is today: that is what each city's daily level is for.
When does grass pollen season start in the UK?
In London, the Copernicus CAMS model's 2023–2025 average puts grass at moderate or above from June to July. Tree pollen comes before it: alder from March to April and birch in April. The tool on this page shows the months for 19 UK and Irish cities.
When is cedar fever season in Texas?
Mountain cedar (Ashe juniper) flowers in winter. Respira's seasonal calendar for the Southwest puts juniper at moderate or above from December to February, which is why Texans can have allergy season at Christmas.
When is ragweed season?
Late summer into autumn. In Chicago, Respira's calendar for the Midwest puts ragweed at moderate or above from August to October, ending with the first hard frost.
Where does the data come from?
UK and Irish rows come from the Copernicus CAMS model at each city's coordinates (via Open-Meteo), averaged over 2023–2025. US rows are Respira's seasonal calendars for each region, the same ones the app uses; they are estimates, not measurements, and are tagged as such.
Is this a forecast for this year?
No. It is the calendar of a typical year. Each season comes earlier or later depending on the weather. Today's level and the forecast for the coming days are on each city's page and in the Respira app.