Skip to main content

Four Highest Eight-Hour Ozone Concentrations in 2025
as of September 14

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 208/04/202512009008/19/202510008407/31/202511007808/26/2025110076
Keller C17207/31/202511008309/10/202511007207/30/202511007203/01/2025110072
Frisco C31/C680109/11/202510008707/30/202511008606/16/202513008509/10/2025080081
Denton Airport South C56/A163/X157109/11/202510008608/13/202511008307/30/202513008209/10/2025110081
Arlington Municipal Airport C61108/24/202511007408/04/202512007208/01/202511007104/10/2025110070
Dallas North No.2 C63/C679107/31/202512008206/16/202510007509/11/202510007209/04/2025110071
Rockwall Heath C69106/16/202511007307/31/202511007209/04/202510006905/31/2025120060
Grapevine Fairway C70/A301/X182109/11/202510007509/10/202511007308/13/202513007308/04/2025100073
Kaufman C71/A304/X071105/07/202513006704/09/202511006704/08/202511006704/07/2025110067
Granbury C73/C681108/26/202511007704/10/202512007604/12/202512006909/10/2025110068
Eagle Mountain Lake C75 105/23/202511007409/11/202510007308/04/202512007308/13/2025120069
Parker County C76108/26/202510008208/04/202513007408/19/202513007309/10/2025100071
Cleburne Airport C77/C682104/10/202512007108/21/202510006704/12/202512006708/26/2025100066
Dallas Hinton St. C401/C60/AH161 302/02/202512005402/03/202511004202/01/202509004201/13/2025100040
Dallas Executive Airport C402108/01/202511007605/07/202511007105/31/202511007004/09/2025110069
Greenville C1006/A198109/04/202510007606/16/202512006804/09/202511006509/11/2025100063
Pilot Point C1032109/11/202511009708/13/202512008105/23/202510008109/10/2025100077
Italy C1044/A323106/09/202511006509/02/202511006408/01/202512006404/12/2025150064
Corsicana Airport C1051104/09/202511007004/12/202513006803/01/202511006804/07/2025120067
Tyler-Longview-Marshall
Longview C19/A127/C644204/09/202513007508/01/202512006909/09/202511006704/08/2025100067
Tyler Airport Relocated C82104/09/202515006804/08/202510006609/09/202512006409/04/2025110064
Karnack C85/AFHP303104/09/202511006602/28/202510005904/08/202510005804/13/2025120057
El Paso-Juarez
Ascarate Park SE C37/A332/A172/X159105/11/202511007907/26/202511007107/15/202511007106/16/2025110071
Chamizal C41/AH126 105/11/202511006708/05/202511006408/08/202510006307/26/2025120063
Socorro Hueco C49/F312108/02/202514006907/26/202511006905/11/202511006807/10/2025110067
Skyline Park C72105/11/202511007607/15/202511006906/11/202510006908/27/2025110067
Ivanhoe C414/F514105/11/202511006207/15/202511005907/10/202511005906/16/2025120059
Ojo De Agua C1021/FG121/FG221108/08/202511007407/26/202511006705/11/202510006708/27/2025110066
Waco
Waco Mazanec C1037104/09/202511007205/13/202511007104/10/202511006904/08/2025100069
Temple Georgia C1045104/09/202511007005/13/202510006904/12/202511006809/10/2025100066
Killeen Skylark Field C1047105/13/202512008204/12/202511007409/10/202509007205/14/2025110071
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 209/13/202510007009/12/202509006509/14/202510006306/02/2025080063
West Orange C9/A141209/04/202511006709/12/202510006009/09/202510005809/14/2025110057
Port Arthur West C28/A128/A228109/09/202511006909/14/202510006009/13/202510005703/01/2025110057
Hamshire C64/C654109/09/202511006403/01/202512006409/13/202510006208/19/2025100061
SETRPC Port Arthur C6281 N05/08/202509006503/01/202512006404/10/202508006304/16/2025100062
SETRPC 40 Sabine Pass C640/C1654107/30/202511007009/04/202510006803/01/202512006809/14/2025090067
SETRPC Mauriceville 42 C642/C311/C6651 N04/16/202510005604/10/202510005603/01/202510005604/09/2025100055
SETRPC 43 Jefferson Co Airport C643109/09/202510007409/13/202510006609/14/202510006203/01/2025110060
Nederland 17th Street C1035109/13/202510006909/14/202510006403/01/202516006309/12/2025090061
Austin
Austin North Hills Drive C3/A322209/10/202510007909/04/202511006808/25/202510006805/21/2025110066
Audubon C38109/10/202510007505/13/202511006804/09/202510006604/12/2025100065
Dripping Springs School C6141 N09/10/202510008205/21/202511007804/11/202511007704/09/2025110077
CAPCOG Lake Georgetown C6901 N09/10/202510006409/12/202514005708/25/202510005309/14/2025110052
Lockhart C16041 N04/09/202511007405/20/202512007104/08/202510007104/12/2025110067
St. Edwards University C16051 N04/11/202511007104/08/202511007104/09/202511007004/12/2025110068
CAPCOG Bastrop CAMS16121 N05/21/202514006905/12/202510006604/09/202511006504/21/2025110064
CAPCOG Elgin C16131 N09/10/202510007505/12/202510006909/12/202512006604/08/2025100066
CAPCOG East Austin C16191 N09/10/202511007909/04/202510007009/09/202511006505/13/2025120064
CAPCOG Round Rock Brushy Creek W C16201 N04/10/202511006705/13/202511006604/09/202510006504/12/2025100064
CAPCOG Taylor Murphy Park C16291 N09/10/202510006709/04/202510006609/12/202514006305/13/2025110063
CAPCOG Lake Kyle Park C16301 N09/10/202509006605/21/202513006504/11/202511006504/08/2025110065
CAPCOG San Marcos Staples Road C16751 N04/11/202511007004/12/202512006604/10/202511006404/09/2025100060
Houston-Galveston-Brazoria
Houston East C1/G316208/03/202509008209/04/202511007603/25/202510007608/18/2025100075
Houston Aldine C8/AF108/X150 203/25/202510008109/13/202509008009/10/202510007507/30/2025120073
Channelview C15/AH115 308/03/202509008509/04/202510007607/30/202511007409/03/2025100070
Northwest Harris Co. C26/A110/X154209/13/202510008609/10/202511008509/12/202510008408/25/2025110080
Hou.DeerPrk2 C35/235/1001/AFH139/FP239107/29/202512009407/24/202511009008/20/202510008807/30/2025110088
Seabrook Friendship Park C45107/30/202511007109/14/202509006905/12/202512006903/01/2025120068
Houston Bayland Park C53/A146 108/20/202510008308/25/202510008008/21/202510007709/10/2025100076
Conroe Relocated C78/A321104/12/202511008004/10/202511008006/02/202510007804/09/2025100078
Manvel Croix Park C84109/09/202510008208/20/202510007608/21/202511007203/01/2025110069
Clinton C403/C304/AH113 308/03/202509008208/18/202511007707/24/202511007508/20/2025090074
Houston North Wayside C405/C1033103/25/202510006709/13/202509006508/03/202509006508/25/2025100064
Houston Monroe C406108/20/202510008107/29/202512007307/30/202512006609/09/2025100064
Lang C408209/10/202510008008/25/202510007805/29/202511007803/25/2025110075
Houston Croquet C409208/20/202510008908/21/202510007909/09/202511007308/25/2025100073
Houston Westhollow C410/C3003108/25/202510007609/10/202510007409/09/202511007008/26/2025090069
Park Place C416108/20/202510008807/29/202512007609/13/202509007308/03/2025090071
Houston Harvard Street C417108/25/202510008409/10/202510008209/13/202510007807/30/2025120078
Sheldon C5511 N03/25/202509006909/04/202509006307/30/202511005904/10/2025080059
Baytown Wetlands Center C5521 N09/04/202509007207/30/202510007207/29/202511007205/12/2025120068
Crosby Library C5531 N09/04/202510007204/10/202508007106/01/202509006105/12/2025130061
West Houston C5541 N08/25/202510008905/29/202510008809/10/202510008705/07/2025090082
La Porte Sylvan Beach C5561 N09/14/202508007909/03/202509007907/29/202511007609/04/2025080074
Mercer Arboretum C5571 N05/27/202510008803/25/202510008604/10/202509007906/02/2025090078
Tom Bass C5581 N08/20/202509008809/09/202510008003/01/202512007708/21/2025100074
Katy Park C5591 N09/10/202510008008/25/202510007805/21/202509007705/29/2025100067
Atascocita C5601 N03/25/202509007109/04/202510006707/30/202511006604/12/2025090066
Meyer Park C5611 N03/25/202510008509/13/202509008409/10/202510007804/10/2025100075
Bunker Hill Village C5621 N09/10/202509008208/25/202509008205/21/202509007305/29/2025100071
Huffman Wolf Road C5631 N03/25/202510008005/27/202509007804/10/202509007404/09/2025090067
HRM-3 Haden Road C603/A114 1 N06/20/202516009608/03/202509009308/18/202510007907/30/2025120078
Wallisville Road C617 1 N08/03/202510007407/30/202511006307/24/202511006303/25/2025100063
Texas City 34th St. C620 1 N05/12/202513007503/01/202512007508/20/202510007003/24/2025110065
Lynchburg Ferry C1015/A165 108/03/202510008909/04/202510007407/30/202511007207/29/2025120070
Lake Jackson C1016 108/21/202509007109/09/202512006805/12/202511006703/01/2025110067
Baytown Garth C1017109/04/202510007608/03/202510007309/03/202510007103/25/2025100071
Galveston 99th St. C1034/A320/X183103/01/202516009708/20/202510009005/12/202513008202/01/2025120082
Oyster Creek C1607 1 N08/21/2025100010005/12/202512006904/11/202511006803/01/2025100068
San Antonio
San Antonio Northwest C23209/10/202510008709/09/202511007908/05/202508007708/24/2025120064
Camp Bullis C58 109/10/202510008704/11/202511007509/09/202510007405/21/2025100071
Calaveras Lake C59105/12/202511007309/10/202509007204/11/202511006804/12/2025110066
Elm Creek Elementary C5011 N06/24/202508009909/10/202510007609/09/202511007104/21/2025110071
Fair Oaks Ranch C5021 N04/11/202512007204/10/202511007105/15/202511007009/10/2025100068
Bulverde Elementary C5031 N05/15/202511008109/10/202510007905/14/202511007605/13/2025110076
New Braunfels Airport C5041 N09/10/202510007109/04/202510006703/01/202510006502/28/2025110061
AACOG City of Garden Ridge C505 1 N09/10/202510009005/12/202512008609/04/202512007605/13/2025110076
Seguin Outdoor Learning Center C5061 N05/12/202512007309/10/202509007103/01/202511006605/21/2025110064
Heritage Middle School C6221 N07/27/2025210010205/12/202511008309/10/202509007805/20/2025130073
CPS Pecan Valley C6781 N05/12/202511006504/21/202511006204/11/202511006204/08/2025110060
Government Canyon C16101 N09/10/202510007905/21/202510007404/21/202511007404/11/2025110074
Corpus Christi-Victoria
Corpus Christi West C4204/08/202510006705/12/202510006505/11/202511006309/03/2025100062
Corpus Christi Tuloso C21105/12/202510006804/08/202510006605/11/202511006404/09/2025080060
Victoria C87105/12/202511006909/08/202511006605/11/202511006604/08/2025090065
Lower Rio Grande Valley
Mission C43/AP143105/12/202510007104/08/202510007105/11/202511006104/09/2025110058
Harlingen Teege C1023104/08/202510006005/12/202510005905/11/202510005704/09/2025100057
Laredo
Laredo College C441 N05/15/202511007505/12/202510007409/03/202511007304/08/2025110069
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.