Horizon AQ · Experimental planning tool

Know the air before you head out.

Enter a U.S. ZIP code and tell us who you're planning for. Horizon AQ publishes a 48-hour outlook only when official observations, daily agency forecasts, hourly atmospheric guidance, and weather data pass conservative quality checks — and flags it clearly when conditions call for extra caution for sensitive groups.

Check an area

Five-digit U.S. ZIP code

Shifts the caution threshold earlier for sensitive groups. Informational only — not medical advice.

Built to say “not enough data”

No forecast is safer than a falsely precise one.

Every request is screened for observation distance and age, source completeness, model agreement, and official forecast coverage. Failed checks are shown directly instead of being hidden behind a number. Choose a health profile above and Horizon AQ will flag the hours that call for extra caution.

01

Fresh official observationWithin the configured distance and age limits.

02

Complete hourly inputsAt least 46 AQ-model hours and 42 NWS hours.

03

Source agreementNo extreme mismatch between AirNow and hourly guidance.

04

Daily agency anchorEnough of the horizon is covered by an official daily forecast.