Wyoming · County air quality · 2024
Weston County, Wyoming
Median AQI 39 (Good). 87.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 87.7%
- Good-air days
- 0
- Unhealthy days
- 60%
- Cleaner than US counties
Weston County's 2024 annual median AQI is 39 (Good), with 87.7% Good days
According to the U.S. EPA Air Quality System, Weston County, Wyoming posted a 2024 median AQI of 39 (Good) across 365 monitored days, with 87.7% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Weston County's 87.7% Good-day share places it cleaner than 60% of US counties in 2024.
- Closest median-AQI peer
- Big Horn County (89.2% Good, median AQI 39) is the closest nationwide median-AQI peer to Weston County.
- 2020–2024 trend
- Weston County's floor-qualifying Good-day share is worsening from 2020 to 2024 (91.5% → 87.7%).
- Median AQI
- Median AQI: 39
According to the 2024 EPA AQS county release on PlainAirData, Weston County, Wyoming ranks #5 of 15 by median AQI (39) and #6 by good-day share (87.7%). San Mateo County, California is #1 of 15 by median AQI (27, 88.1% Good days) at good-day-share #5 ≠ Chattooga County, Georgia #1 by good-day share (96.3%, median AQI 39) at median-AQI #5.
Annual release change
What changed in the 2024 EPA annual release
- Weston County's peak single-day AQI rose from 90 to 136 between the 2023 and 2024 EPA annual releases, a change of +46 points.
- Weston County's Good-day share fell from 90.8% to 87.7% between the 2023 and 2024 EPA annual releases, a change of -3.1 percentage points.
- Weston County's median AQI fell from 42 to 39 between the 2023 and 2024 EPA annual releases, a change of -3 points.
Data updated August 2026
- Good · 320 d · 87.7%
- Moderate · 40 d · 11.0%
- USG · 5 d · 1.4%
How did Weston County's air break down in 2024?
Across 365 monitored days, 320 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 136 (USG).
EPA AQS →Share of monitored days at AQI 0-50 (Good band).
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
Where Weston County sits nationally
COUNT-derived placement among 951 US counties with at least 100 monitored days in 2024. Weston County's Good-day share is 87.7% - cleaner than 60% of that comparison set.
Weston County Good-day share vs. every US county
Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
87.7% Cleaner than 60% higher than 60% of 951 US counties
Each bar is a band; taller bars hold more US counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2024
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Weston County.
- Ozone · 365 days · 100.0%
2024 daily-monitor rhythm in Weston County
Month-by-month median AQI from EPA day-level county monitors (365 reported days in 2024). Jul posted the highest typical readings (median AQI 61, peak 136); Nov was cleanest at median 33. Summer months (Jun–Aug) averaged median AQI 51 vs 34 in Dec–Feb.
Five-year seasonal record
EPA day-level county files · 2020–20241,771 daily readings show a recurring local pattern: Jul has the highest matched-month median AQI (54), while Dec is lowest (34). Each cell is that month’s median daily AQI, not a current-air forecast.
Lower AQI is better. The colors summarize EPA AQI bands; gaps mean the county had no day-level record for that month.
Health Impact Assessment
Weston County's air quality is rated Good based on 87.7% good air days. No unhealthy air days were recorded in 2024.
Air quality was acceptable on 87.7% of monitored days in 2024, with a median AQI of 39. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 365 of 365 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Weston County. Highest Good-day share: 2022 (94.8%, 344 of 363 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 323 | 29 | 1 | 0 | 40 | 119 |
| 2021 | 282 | 61 | 0 | 0 | 41 | 100 |
| 2022 | 344 | 19 | 0 | 0 | 40 | 64 |
| 2023 | 315 | 32 | 0 | 0 | 42 | 90 |
| 2024 | 320 | 40 | 5 | 0 | 39 | 136 |
How does Weston County compare?
How Weston County compares
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Weston County, Wyoming · 2020–2025
Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.
Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.