Data / Highest daily Air Quality Index (US EPA) / Winchester city

Highest daily Air Quality Index (US EPA) in Winchester city

Highest daily Air Quality Index (US EPA) in Winchester city was 18 in 2020, according to the U.S. Environmental Protection Agency. That is down 6 from 2019.

2020, index18
Change on 2019-6
Series high671997
Series low182014

Next release: Tuesday, 13 July 2027, estimated by Invokely from past publication dates (low confidence), not announced by the publisher. Release calendar

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Highest daily Air Quality Index (US EPA) in Winchester city, 1989 to 2020

1020304050607019891994199920042009201420201989: 53 index1990: 61 index1991: 53 index1992: 37 index1993: 54 index1994: 52 index1995: 46 index1996: 42 index1997: 67 index1998: 48 index1999: 45 index2000: 46 index2001: 47 index2002: 48 index2003: 50 index2004: 44 index2005: 38 index2006: 37 index2007: 47 index2008: 33 index2009: 27 index2010: 40 index2011: 32 index2012: 30 index2013: 19 index2014: 18 index2015: 31 index2016: 25 index2017: 19 index2018: 20 index2019: 24 index2020: 18 index02040608019892000201120201989: 53 index1990: 61 index1991: 53 index1992: 37 index1993: 54 index1994: 52 index1995: 46 index1996: 42 index1997: 67 index1998: 48 index1999: 45 index2000: 46 index2001: 47 index2002: 48 index2003: 50 index2004: 44 index2005: 38 index2006: 37 index2007: 47 index2008: 33 index2009: 27 index2010: 40 index2011: 32 index2012: 30 index2013: 19 index2014: 18 index2015: 31 index2016: 25 index2017: 19 index2018: 20 index2019: 24 index2020: 18 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 32 values
Periodindex
202018
201924
201820
201719
201625
201531
201418
201319
201230
201132
201040
200927
200833
200747
200637
200538
200444
200350
200248
200147
200046
199945
199848
199767
199642
199546
199452
199354
199237
199153
199061
198953

Winchester city compared with nearby places

Albemarle County: 70 indexArlington County: 90 indexCaroline County: 64 indexCarroll County: 15 indexCharles City County: 67 indexChesterfield County: 61 indexFairfax County: 100 indexFauquier County: 61 indexFrederick County: 81 indexGiles County: 67 indexHanover County: 64 indexHenrico County: 71 indexLoudoun County: 108 indexMadison County: 55 indexPrince Edward County: 49 indexPrince William County: 74 indexRoanoke County: 72 indexRockbridge County: 54 indexRockingham County: 77 indexStafford County: 84 indexWythe County: 61 indexBristol city: 60 indexHampton city: 68 indexHopewell city: 15 indexLynchburg city: 59 indexNorfolk city: 64 indexRichmond city: 80 indexSalem city: 69 indexSuffolk city: 67 indexVirginia Beach city: 74 indexWinchester city: 18 index
  • Under 55
  • 55 to 61
  • 61 to 67
  • 67 to 71
  • 71 to 80
  • 80 and over
  • No data
Highest daily Air Quality Index (US EPA), 2020, index. Winchester city is outlined. Same source and period for every area shown. Source: U.S. Environmental Protection Agency. Boundaries: U.S. Census Bureau cartographic boundary files.

Rankings

Definition

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

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How to cite

U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: highest daily AQI (Highest daily Air Quality Index (US EPA), Winchester city, 1989 to 2020) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), Winchester city, 1989 to 2020. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/highest-daily-air-quality-index/winchester-city-virginia. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Highest daily Air Quality Index (US EPA), Winchester city, 1989 to 2020. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/highest-daily-air-quality-index/winchester-city-virginia.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), Winchester city, 1989 to 2020 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/highest-daily-air-quality-index/winchester-city-virginia (Accessed: 12 October 2026).

BibTeX
@misc{environmental_highest_daily_air_quality_2020,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), Winchester city, 1989 to 2020}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/winchester-city-virginia. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download\_files.html\#Annual. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), Winchester city, 1989 to 2020
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/en/highest-daily-air-quality-index/winchester-city-virginia
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/winchester-city-virginia.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

What is the highest daily Air Quality Index (US EPA) in Winchester city?

Highest daily Air Quality Index (US EPA) in Winchester city was 18 in 2020, according to the U.S. Environmental Protection Agency. That is down 6 from 2019.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: highest daily AQI. Retrieved by Invokely on 2026-10-12.

What was the highest highest daily Air Quality Index (US EPA) in Winchester city?

67 in 1997, the highest value since 1989 in this series.

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