Metro area air quality · 2025
Hilo, HI
Median AQI 32 (Good). 86.0% of monitored days rated Good across this metro's EPA monitoring network.
- 32
- Median AQI
- 86.0%
- Good-air days
- 0
- Unhealthy days
- 80%
- Cleaner than US metros
Hilo, HI posted a 2025 median AQI of 32 (Good) with 86.0% Good days
According to the U.S. EPA Air Quality System, the Hilo, HI CBSA recorded a median AQI of 32 across 365 monitored days in 2025, with 86.0% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US metros
- The Hilo, HI CBSA's 86.0% Good-day share places it cleaner than 80% of US metros in 2025.
- Closest median-AQI peer
- Crescent City, CA (81.8% Good, median AQI 32) is the closest nationwide median-AQI peer to Hilo, HI.
- 2020–2025 Good-day shift
- Hilo, HI's Good-day share moved -10.1 points from 2020 to 2025 (median AQI +9).
- Median AQI
- Median AQI: 32
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
The Hilo, HI metro runs good on the EPA scale, cleaner than most US metros, a median AQI of 32 with 86.0% of 365 monitored days in the Good band.
- 32
- median AQI · Good
- 86.0%
- days rated Good
- 80%
- cleaner than US metros
- 93
- worst single reading
No day crossed into the Unhealthy tier across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Hilo, HI metro's Good-day share fell from 97.0% to 86.0% between the 2024 and 2025 EPA annual releases, a change of -11.0 percentage points.
- Hilo, HI metro's median AQI rose from 21 to 32 between the 2024 and 2025 EPA annual releases, a change of +11 points.
- Hilo, HI metro's peak single-day AQI rose from 75 to 93 between the 2024 and 2025 EPA annual releases, a change of +18 points.
Insights: Hilo, HI metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 32 over 365 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 314 Good days (86%), 51 Moderate (14%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 53 while the highest single-day reading hit 93 (Moderate). Metro residents averaged roughly 25.8 clean-air days per 30-day window across the reporting year.
Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -10.1 points and the median AQI moved +9 points, which classifies the multi-year trajectory as worsening. The metro recorded no Unhealthy-tier days in this annual dataset. Metros with comparable AQI profiles include Crescent City, CA (81.8% good, AQI 32); Laconia, NH (88.8% good, AQI 32); Athens, OH (83.4% good, AQI 31).
Air Quality Summary
Median AQI
32
Good
Good Days
86.0%
314 of 365 days
Max AQI
93
Moderate
Health Grade
Good
90th pct: 53
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
314
86%
Moderate
51
14%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Hilo, HI metro area's air quality is rated Good based on 86.0% good air days. No unhealthy air days were recorded in 2025.
Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.
How does the Hilo, HI metro compare?
How Hilo, HI compares
5-Year Air Quality Trend
Air quality is worsening in the Hilo, HI metro. Highest Good-day share: 2024 (97.0%, 355 of 366 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 352 | 14 | 0 | 23 | 83 |
| 2021 | 336 | 29 | 0 | 27 | 65 |
| 2022 | 328 | 37 | 0 | 33 | 71 |
| 2023 | 336 | 29 | 0 | 23 | 71 |
| 2024 | 355 | 11 | 0 | 21 | 75 |
| 2025 | 314 | 51 | 0 | 32 | 93 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Hilo, HI (32).
Crescent City, CA
Median AQI 32 · 81.8% Good-day share
Laconia, NH
Median AQI 32 · 88.8% Good-day share
Athens, OH
Median AQI 31 · 83.4% Good-day share
Bangor, ME
Median AQI 33 · 84.2% Good-day share
Bellingham, WA
Median AQI 31 · 94.0% Good-day share
Clarksburg, WV
Median AQI 33 · 72.4% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Hilo, HI's 0 (independent of median AQI).
Aberdeen, SD
0 unhealthy-or-worse days · median AQI 27
Aberdeen, WA
0 unhealthy-or-worse days · median AQI 22
Adrian, MI
0 unhealthy-or-worse days · median AQI 41
Akron, OH
0 unhealthy-or-worse days · median AQI 45
Albany, GA
0 unhealthy-or-worse days · median AQI 46
Albany, OR
0 unhealthy-or-worse days · median AQI 27
More Air Quality Data
Explore EPA air quality rankings and guides across U.S. metros and counties.
Cleanest Metro Areas
U.S. metros ranked by their share of Good air-quality days.
Worst Air Quality
Counties and metros with the most unhealthy air days.
All Metro Areas
Annual AQI by CBSA for every monitored U.S. metro area.
Best and Worst City Air
What drives urban air quality and how metro areas compare.
Air Quality Guides
Frequently Asked Questions
What is the air quality in the Hilo, HI metro area? ▼
How many unhealthy air days does Hilo, HI have? ▼
Is air quality in Hilo, HI getting better or worse? ▼
What does AQI 32 mean for health? ▼
What is the 90th percentile AQI for Hilo, HI? ▼
How does Hilo, HI compare to other metro areas? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025
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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.