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Four Highest Eight-Hour Ozone Concentrations in 2025
as of January 16

Use this form to retrieve the four highest eight-hour ozone concentration averages from data collected at TCEQ monitoring sites beginning December 14, 2005 through today. Although this is our most current data, it is not considered official until it has been certified by our technical staff. This information is updated hourly. All times shown are in Local Standard Time.

The table below lists the four highest daily maximum eight-hour ozone concentrations measured in 2025 in each community where the TCEQ measures ozone. Concentrations that are rated Moderate or higher are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) The fourth-highest average is in bold black (unless it is highlighted). All ozone measurements are in parts per billion. Times are shown in 24-hour format and correspond to the beginning of the eight hour average.

Use the selection boxes below to customize this report. You may select a different year or a different report format. If you want to cut and paste data from this web page into another application, such as a spreadsheet, select the comma-delimited format. Click on the Generate Report button once you have made your selections.

YearReport Format
Highlight with AQI colors
Area Monitoring Site POC Highest Second Highest Third Highest Fourth Highest
Date Time Value Date Time Value Date Time Value Date Time Value
Dallas-Fort Worth
Ft. Worth Northwest C13/AH302 201/16/202510003601/12/202511003601/11/202511003401/06/2025100034
Keller C17201/16/202511003901/13/202510003701/12/202511003701/11/2025120037
Frisco C31/C680101/13/202509003701/12/202510003601/16/202510003501/15/2025100035
Denton Airport South C56/A163/X157101/16/202510004001/12/202510003501/13/202510003401/11/2025130034
Arlington Municipal Airport C61101/11/202512003701/12/202512003601/06/202509003501/03/2025110034
Dallas North No.2 C63/C679101/12/202511003501/11/202512003501/06/202509003401/13/2025090033
Rockwall Heath C69101/13/202509003601/12/202512003501/11/202511003501/15/2025100034
Grapevine Fairway C70/A301/X182101/12/202511003801/16/202510003701/06/202509003701/11/2025100034
Kaufman C71/A304/X071101/11/202512004201/15/202511004101/13/202510004101/12/2025140041
Granbury C73/C681101/15/202511004001/11/202511004001/06/202511004001/16/2025120038
Eagle Mountain Lake C75 101/16/202512004201/13/202509003701/11/202513003701/14/2025110036
Parker County C76101/16/202513004401/11/202512004001/15/202510003801/14/2025090038
Cleburne Airport C77/C682101/16/202512004001/11/202513003701/06/202509003701/14/2025110035
Dallas Hinton St. C401/C60/AH161 301/13/202510004001/12/202512004001/11/202511003601/06/2025100036
Dallas Executive Airport C402101/16/202510003801/12/202512003801/13/202510003701/11/2025110037
Greenville C1006/A198101/15/202510003801/14/202509003701/06/202509003601/16/2025100034
Pilot Point C1032101/16/202512003901/13/202509003801/12/202511003701/06/2025090037
Italy C1044/A323101/16/202512003801/06/202509003501/03/202511003501/14/2025080033
Corsicana Airport C1051101/16/202512004401/13/202509004301/11/202511004201/15/2025100041
Tyler-Longview-Marshall
Longview C19/A127/C644201/12/202511004401/16/202510004301/03/202511004001/13/2025110039
Tyler Airport Relocated C82101/16/202510004201/03/202511004101/15/202511003901/13/2025100039
Karnack C85/AFHP303101/16/202510004001/13/202510003701/15/202511003601/06/2025090036
El Paso-Juarez
Ascarate Park SE C37/A332/A172/X159101/16/202511004101/05/202510003801/01/202509003801/15/2025090037
Chamizal C41/AH126 101/16/202510004101/05/202510004101/04/202519004001/15/2025090038
Socorro Hueco C49/F312101/16/202510004401/13/202511004101/05/202509004101/04/2025120038
Skyline Park C72101/16/202510004401/04/202512004401/05/202509004301/01/2025090042
Ivanhoe C414/F514101/05/202509003601/04/202520003501/16/202510003401/01/2025090034
Ojo De Agua C1021/FG121/FG221101/05/202511004101/04/202512004001/14/202514003901/15/2025110037
Waco
Waco Mazanec C1037101/13/202511004001/11/202512004001/16/202511003801/15/2025110038
Temple Georgia C1045101/15/202510004001/11/202512004001/13/202510003901/06/2025090039
Killeen Skylark Field C1047101/11/202511004101/13/202510004001/12/202512004001/06/2025100040
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 201/11/202510003701/16/202510003501/06/202509003501/03/2025100035
West Orange C9/A141201/03/202511003801/16/202510003701/11/202511003501/05/2025080035
Port Arthur West C28/A128/A228101/03/202512003501/06/202511003301/16/202511003201/11/2025120032
Hamshire C64/C654101/03/202512004301/16/202511003901/13/202510003701/11/2025100037
SETRPC 40 Sabine Pass C640/C1654101/03/202512003801/11/202510003701/06/202512003701/13/2025110036
SETRPC 43 Jefferson Co Airport C643101/03/202510004001/16/202510003901/11/202510003701/13/2025110036
Nederland 17th Street C1035101/03/202512004101/16/202511003701/11/202510003501/06/2025110035
Austin
Austin North Hills Drive C3/A322201/11/202511004001/06/202510004001/16/202511003901/12/2025130039
Audubon C38101/11/202511003801/06/202509003801/12/202511003701/16/2025140036
Houston-Galveston-Brazoria
Houston East C1/G316201/05/202506003501/11/202512003401/16/202510003101/04/2025100031
Houston Aldine C8/AF108/X150 201/06/202509003801/07/202510003601/05/202506003601/03/2025100034
Channelview C15/AH115 301/16/202510003801/06/202509003501/13/202510003401/05/2025060034
Northwest Harris Co. C26/A110/X154201/16/202510004301/06/202511003901/11/202510003801/03/2025110038
Hou.DeerPrk2 C35/235/1001/AFH139FP239101/16/202510003901/03/202514003701/11/202511003601/06/2025100036
Seabrook Friendship Park C45101/11/202511003601/03/202514003601/06/202510003501/05/2025030032
Houston Bayland Park C53/A146 101/16/202510003801/11/202511003701/06/202511003701/05/2025060037
Conroe Relocated C78/A321101/16/202510004101/13/202510003701/03/202510003701/11/2025100036
Manvel Croix Park C84101/01/202510003701/05/202507003501/11/202510003401/06/2025100034
Clinton C403/C304/AH113 301/13/202510003501/16/202511003301/06/202510003201/01/2025100032
Houston North Wayside C405/C1033101/13/202510003201/16/202510002901/07/202509002901/06/2025090029
Houston Monroe C406101/05/202507003301/03/202516003201/11/202510003001/01/2025100030
Lang C408201/05/202506003301/11/202510003201/06/202510003101/16/2025100030
Houston Croquet C409201/11/202512003601/05/202506003501/16/202510003401/06/2025090034
Houston Westhollow C410/C3003101/16/202511003701/11/202510003601/06/202510003601/01/2025100035
Park Place C416101/03/202517003501/05/202507003401/13/202509003301/11/2025100033
Houston Harvard Street C417101/16/202510003201/03/202515003101/01/202510003101/13/2025090030
Sheldon C5511 N01/16/202511004101/06/202510003901/13/202510003801/07/2025110037
Baytown Wetlands Center C5521 N01/16/202510003801/13/202511003801/06/202510003701/03/2025130037
Crosby Library C5531 N01/06/202510004001/07/202511003701/03/202511003601/11/2025100035
West Houston C5541 N01/01/202510003701/03/202513003601/05/202505003501/04/2025100030
La Porte Sylvan Beach C5561 N01/11/202513003601/03/202515003601/06/202510003501/04/2025100034
Mercer Arboretum C5571 N01/16/202510004001/13/202510003901/07/202511003801/06/2025100038
Tom Bass C5581 N01/11/202511003801/05/202505003701/03/202516003701/13/2025090035
Katy Park C5591 N01/13/202509003201/11/202511003201/06/202510003201/01/2025110032
Atascocita C5601 N01/16/202511003501/13/202510003501/06/202510003501/03/2025110034
Meyer Park C5611 N01/16/202511004501/13/202510003801/06/202510003801/11/2025100036
Bunker Hill Village C5621 N01/16/202511003601/13/202510003401/11/202512003401/06/2025110034
Huffman Wolf Road C5631 N01/16/202510003901/06/202510003501/13/202510003401/03/2025110034
Lynchburg Ferry C1015/A165 101/05/202507003701/06/202509003501/11/202511003301/07/2025090031
Lake Jackson C1016 101/13/202510004101/05/202502004101/11/202510003901/04/2025220039
Baytown Garth C1017101/16/202510004001/13/202509003701/06/202510003601/11/2025110035
Galveston 99th St. C1034/A320/X183101/11/202514004401/04/202510004101/03/202515004101/16/2025130039
Oyster Creek C1607 1 N01/04/202507003901/03/202514003901/01/202511003401/02/2025200029
San Antonio
San Antonio Northwest C23201/11/202511003601/12/202510003501/06/202509003501/15/2025100034
Camp Bullis C58 101/01/202510003201/02/202505001901/16/202511001401/11/2025100013
Calaveras Lake C59101/16/202510004001/06/202511004001/12/202512003901/11/2025100037
Heritage Middle School C6221 N01/16/202511004801/11/202511004501/06/202509004401/12/2025110043
Corpus Christi-Victoria
Corpus Christi West C4201/16/202512004401/13/202510004401/11/202511003901/06/2025110039
Corpus Christi Tuloso C21101/13/202510004401/16/202511004301/11/202511004001/12/2025100038
Victoria C87101/16/202511004401/11/202511004101/06/202510004101/13/2025100039
Lower Rio Grande Valley
Mission C43/AP143101/16/202511003801/13/202510003701/06/202510003201/05/2025110032
Harlingen Teege C1023101/16/202511004201/13/202512004201/04/202511003901/05/2025060038
Laredo
Laredo College C441 N01/16/202510004601/13/202510004101/02/202512004001/11/2025100038
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.
 N - Data from this instrument does not meet EPA quality assurance criteria and cannot be used for regulatory purposes.

Interpreting the AQI

Air Quality Index

Each NAAQS pollutant has a separate AQI scale, with an AQI rating of 100 corresponding to the concentration of the Federal Standard for that pollutant. Additional information about the AQI and how it can be used is available from the EPA's AirNow web site.

Place your mouse pointer over the scale displayed above to view information about the Air Quality Index, and each of the rating levels.

The actual index calculation is different for each parameter measured and is specified by the EPA. The following table shows the various breakpoints used in calculating the AQI.

AQI Breakpoint Definitions
AQI Range 1hr Ozone
in ppm		 8hr Ozone
in ppm
0 - 50 Not Defined 0 - 0.054
51 - 100 Not Defined 0.055 - 0.070
101 - 150 0.125 - 0.164 0.071 - 0.085
151 - 200 0.165 - 0.204 0.086 - 0.105
201 - 300 0.205 - 0.404 0.106 - 0.200
301 - 400 0.405 - 0.504 Not Defined
401 - 500 Not Defined Not Defined
500+ Not Defined Not Defined
  • The AQI for ozone is based on either the peak eight-hour running average since midnight OR the peak one-hour measurement since midnight.

PLEASE NOTE:  This data has not been verified by the TCEQ and may change. This is the most current data, but it is not official until it has been certified by our technical staff. Data is collected from TCEQ ambient monitoring sites and may include data collected by other outside agencies. This data is updated hourly. All times shown are in local standard time unless otherwise indicated.

Following EPA reporting guidelines, negative values may be displayed in our hourly criteria air quality data, down to the negative of the EPA listed Method Detection Limit (MDL) for the particular instrument that made the measurements. The reported concentrations can be negative due to zero drift in the electronic instrument output, data logger channel, or calibration adjustments to the data. Prior to 1/1/2013, slightly negative values were automatically set to zero.