Ozone Forecast Program

The TCEQ informs the public a day in advance when conditions are forecast to be favorable for high ozone levels in any of nine metropolitan areas so citizens, businesses, and industry can take steps to reduce the pollutants that contribute to ozone formation.

• Today's Ozone Forecast
• Sign up to Receive Forecasts by E-Mail
• Program Background
  • What is an Ozone Forecast?
  • Metropolitan Areas Participating and Ozone Season Dates

Program Background

What is an Ozone Forecast?

Ozone forecasts are made daily during the ozone forecast season for each of nine metropolitan areas. Each forecast is a simple yes or no prediction for the question, Will ozone levels reach or exceed a target level for a particular area?

TCEQ meteorologists use a set of criteria from historic meteorological data, ozone measurements, and ozone prediction models to make these predictions.

When they forecast an Ozone Action Day, the meteorologists contact the National Weather Service, which then broadcasts the information across its weather wire.

The agency also contacts officials in the affected area, and that community's clean air coalitions notify local media, government, business, and industry.

The forecasts are made, in most cases, a day in advance by 2 p.m. local time and are valid for the next day. The only exception is for the Houston area, where the forecast can be updated as late as 9 a.m. local time on the same day that the forecast is in effect. The forecast target level for all areas is the U.S. EPA Air Quality Index (AQI) Level Orange, which corresponds to an 8-hour average of 76 ppb or a 1-hour average of 125 ppb. In the Houston and Dallas-Fort Worth areas, forecasts for AQI Level Red may also be issued and the target for these forecasts is an 8-hour average of 96 ppb or a 1-hour average of 165 ppb.

The ozone forecast seasons do not necessarily correspond to the "ozone seasons" defined for regulatory purposes by EPA (40 CFR Part 58 Appendix D, Table D3) and may differ.

Participating Metropolitan Areas and Their Ozone forecast season Dates

Each day during ozone forecast season (roughly March through November in Texas), the TCEQ forecasts ozone levels for nine metropolitan areas: