City report · California, United States
Modesto Air quality today
Air quality in Modesto currently reads AQI 77 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Air quality right now
AQI 77
Moderate
- PM2.5, fine particles (µg/m³)
- 23.3
- tree cover
- 25.5%
- trees in this area
- 80.1K
- more trees needed
- 14.1K
Measured across a 1.2 mi (2 km) radius around Downtown Modesto, Modesto, CA, USA (4.9 sq mi), from a satellite image of Sep 15, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Modesto · AQI 77 (Moderate)
Modesto's tree count comes to 80,111 trees across 4.9 sq mi (12.57 km²), 4 points below the 30% tree-cover level considered healthy for this area, so roughly 14,137 more trees would close the gap.
Air quality detail
Air quality in Modesto today: AQI 77, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 06:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.
Ground station · Modesto - 14th Stree, 0.2 mi (400 m) away
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
23.3
PM10
36.0
NO₂
—
O₃
15.7
SO₂
—
CO
—
Data: OpenAQ · AirNow
- Outdoor exercise
- Fine for most people; unusually sensitive people should take long or hard exercise easier
- Windows
- Fine to open; close them if you are sensitive to pollution
- Mask
- Not needed for most people
- Air purifier
- Worth running if you are sensitive
Over the last 7 days, the CAMS air-quality model put Modesto's daily AQI at 70 on average, from 61 on Nov 5 to an hourly peak of 123 on Nov 6.
Where Modesto stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Modesto: Below target
25.5% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).
Trees in this area
80,111
Target trees
94,248
More trees needed
14,137
CO₂ if planted / yr
311.0 t
Deforestation · 2001–2025
How much forest has Modesto lost?
Since 2001, the area within 10 km of Modesto has lost about 5,580 acres (2,260 hectares) of forest (about 4,200 football fields): 53% of the forest it had in 2000. Most of it (over 99%) was deforestation, forest cleared for good, mainly for farms, pasture and plantations.
2017: satellite photo from September 2017 of a 5 × 5 km area about 7 km west of the city center.
- Forest lost since 2001
- 5,580 acres (2,260 ha)about 4,200 football fields
- Share of its forest
- 53%of what there was in 2000
- Cleared for good
- 5,560 acres (2,250 ha)deforestation: turned into farms, mines or towns
Forest loss has stayed about the same: about 286 acres (116 hectares) a year in 2021–2025, against 281 acres (114 hectares) a year in 2016–2020. The worst year was 2023, when about 470 acres (190 hectares) of forest were lost.
Acres of forest lost each year
Show the figures as a table
| Year | Cleared for good | Can grow back | Total |
|---|---|---|---|
| 2001 | 50 acres (20 ha) | under 1 ha | 51 acres (21 ha) |
| 2002 | 63 acres (25 ha) | under 1 ha | 63 acres (26 ha) |
| 2003 | 85 acres (34 ha) | under 1 ha | 86 acres (35 ha) |
| 2004 | 92 acres (37 ha) | under 1 ha | 92 acres (37 ha) |
| 2005 | 217 acres (88 ha) | under 1 ha | 218 acres (88 ha) |
| 2006 | 206 acres (84 ha) | 3 acres (1 ha) | 210 acres (85 ha) |
| 2007 | 216 acres (87 ha) | under 1 ha | 216 acres (87 ha) |
| 2008 | 231 acres (94 ha) | under 1 ha | 233 acres (94 ha) |
| 2009 | 267 acres (108 ha) | under 1 ha | 267 acres (108 ha) |
| 2010 | 282 acres (114 ha) | under 1 ha | 282 acres (114 ha) |
| 2011 | 339 acres (137 ha) | under 1 ha | 339 acres (137 ha) |
| 2012 | 297 acres (120 ha) | 2 acres (1 ha) | 299 acres (121 ha) |
| 2013 | 91 acres (37 ha) | under 1 ha | 91 acres (37 ha) |
| 2014 | 186 acres (75 ha) | under 1 ha | 186 acres (75 ha) |
| 2015 | 107 acres (43 ha) | under 1 ha | 108 acres (44 ha) |
| 2016 | 199 acres (81 ha) | under 1 ha | 200 acres (81 ha) |
| 2017 | 381 acres (154 ha) | under 1 ha | 381 acres (154 ha) |
| 2018 | 351 acres (142 ha) | under 1 ha | 351 acres (142 ha) |
| 2019 | 287 acres (116 ha) | under 1 ha | 287 acres (116 ha) |
| 2020 | 189 acres (77 ha) | under 1 ha | 189 acres (77 ha) |
| 2021 | 376 acres (152 ha) | under 1 ha | 376 acres (152 ha) |
| 2022 | 182 acres (74 ha) | under 1 ha | 182 acres (74 ha) |
| 2023 | 470 acres (190 ha) | under 1 ha | 470 acres (190 ha) |
| 2024 | 289 acres (117 ha) | under 1 ha | 289 acres (117 ha) |
| 2025 | 114 acres (46 ha) | under 1 ha | 114 acres (46 ha) |
What is causing deforestation around Modesto?
- Farms, pasture and plantationscleared for good98% · 5,460 acres (2,210 ha)
- Towns and roadscleared for good1.9% · 104 acres (42 ha)
Also: unknown causes.
Causes for 2025 are estimates, based on what caused forest loss in the same places up to 2024.
Forest gained and lost, 2000–2020
- Forest in 2000
- 8,420 acres (3,410 ha)
- Forest in 2020
- 7,710 acres (3,120 ha)
- Overall change
- −702 acres (284 ha)less forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Modesto shrank from about 8,420 acres (3,410 hectares) to 7,710 acres (3,120 hectares), a net loss of about 702 acres (284 hectares) (−8.3%). New forest grew on about 1,190 acres (480 hectares), but 1,890 acres (765 hectares) were lost.
These 2000 and 2020 maps, from the University of Maryland, count any land with trees taller than 5 m as forest, including plantations and orchards. Forest that was cut or burned and had grown back by 2020 counts in both years, so the loss here is smaller than the yearly figures.
These figures cover everything within 10 km of the city center, a wider area than the report above, because forest is usually lost at a city's edges.
Source: Hansen/UMD/Google/USGS/NASA, Global Forest Change (GFC-2025-v1.13); causes: WRI/Google DeepMind drivers of forest loss; both CC BY 4.0, summed by Airleaf for each area. Forest gained and lost 2000–2020: Potapov et al. 2022, UMD GLAD Global Land Cover and Land Use Change, CC BY 4.0. Images: contains modified Copernicus Sentinel data. How it's measured
In the same region
Measured cities near Modesto
Same 2 km radius, same index — so they compare directly.
- Stockton43.8 km
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- Air quality
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- Antioch81.9 km
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- Air quality
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- San Jose86.0 km
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- Air quality
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- Fremont88.0 km
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- Air quality
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- Elk Grove91.7 km
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- Tree cover
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- Air quality
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- Hayward95.5 km
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- Tree cover
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- Air quality
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Frequently asked
Questions about Modesto
What is the air quality (AQI) in Modesto right now?
The latest reading for Modesto shows an AQI of 77 (Moderate), measured Nov 11, 06:00 local time by the Modesto - 14th Stree ground monitoring station, 0.2 mi (400 m) away, via OpenAQ. The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Modesto today?
At AQI 77 (Moderate): fine for most people; unusually sensitive people should take long or hard exercise easier. Windows: fine to open; close them if you are sensitive to pollution. Masks: not needed for most people. The reading changes through the day, so check again before a long run or ride.
What has the air quality in Modesto been like this week?
Over the last 7 days, the CAMS air-quality model put Modesto's daily AQI at 70 on average, from 61 on Nov 5 to an hourly peak of 123 on Nov 6. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
How much forest has the area around Modesto lost since 2001?
Since 2001, the area within 10 km of Modesto has lost about 5,580 acres (2,260 hectares) of forest (about 4,200 football fields): 53% of the forest it had in 2000. Most of it (over 99%) was deforestation, forest cleared for good, mainly for farms, pasture and plantations. Forest loss has stayed about the same: about 286 acres (116 hectares) a year in 2021–2025, against 281 acres (114 hectares) a year in 2016–2020. Comparing satellite maps from 2000 and 2020, the forest around Modesto shrank from about 8,420 acres (3,410 hectares) to 7,710 acres (3,120 hectares), a net loss of about 702 acres (284 hectares) (−8.3%). New forest grew on about 1,190 acres (480 hectares), but 1,890 acres (765 hectares) were lost.
What is the tree count in Modesto?
Modesto has an estimated 80,111 trees across the 4.9 sq mi (12.57 km²) measured — 25.5% tree cover, 4 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Modesto need?
Modesto needs roughly 14,137 more trees to close a 4-point shortfall against its 30% tree-cover target — about 311.0 t of extra CO₂ absorbed per year once grown.
How are Modesto's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Downtown Modesto, via OpenAQ; the 7-day trend is the Open-Meteo / CAMS model's estimate. Tree cover is measured from Sentinel-2 L2A (ESA Copernicus) via Earth Search satellite imagery at 10 m detail across a 1.2 mi (2 km) radius around Downtown Modesto; the tree count is an estimate derived from that cover.
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