How to choose a pollen forecast app
Nearly every pollen app shows you a number. Very few tell you where that number came from, or that a different app will give you a different one for the same street on the same morning. Here is how to judge them.
Five things that actually matter
1. Does it tell you which plant?
This is the single biggest differentiator. If you react to ragweed but not grass, a combined index is close to useless — it can read "high" on a day that is entirely harmless to you. Look for an app that names plants and gives each its own level.
2. Does it warn you in advance, or only that morning?
Antihistamines generally work better started before exposure. An app that tells you at 9am that today is bad has told you too late.
3. Where does the severity come from?
Almost all pollen numbers are model forecasts, not measurements. Some apps resell the same underlying feed as each other — WeatherBug and Pollen.com publish the identical scale, bands and allergen lists, for example. Two apps agreeing does not mean two sources agree.
4. What does it do with your data?
Many allergy apps ask for an account, precise location, and carry ad SDKs. A ZIP code is enough to forecast pollen. Anything more is worth questioning.
5. Are the notifications usable?
One combined "pollen is high" alert every day trains you to ignore it. Per-allergen alerts, at a level you choose, stay meaningful.
The uncomfortable part: they disagree
We compared two widely used sources across 175 place-days in 35 US cities. They agreed on whether a day was bad about 51% of the time. The correlation was weak, and could not be fixed by rescaling. Against measured counts from certified counting stations, one tracked reality and the other ran high. Full data here.
What to take from that: never compare a number across apps, and put more weight on direction and on which plant than on the absolute value.
A quick checklist
| Question | Good answer |
|---|---|
| Which plants are in the air today? | Named, individually, with levels |
| Which plants next Saturday? | Also named — not just a number |
| Can I get alerts for only ragweed? | Yes, per allergen |
| How far ahead does it warn me? | Days, repeated as it nears |
| Does it need an account? | No |
| Does it say where its data comes from? | Yes, plainly |
Where Pollenary lands
Pollenary was built around the first two questions: which plant, and how far ahead. It names plants for every day of a 5-day forecast, sends one alert per allergen, needs no account, and states its sources. Its weakness is honest too — history starts when you install it, and it does not report mold severity, because our severity source does not.
Pollen levels are a forecast, not a medical measurement. Pollenary is not a medical device and does not diagnose or treat any condition. Talk to a doctor about your allergies.