What is the air quality in Waltham today?

The current Air Quality Index (AQI) in Waltham is 18 (Good). PM2.5 concentration is 4.33 µg/m³.

What is the temperature in Waltham right now?

The current temperature in Waltham is 34.1°C (feels like 37.7°C). Humidity is 43.2% and wind speed is 61.4 km/h.

Is it safe to go outside in Waltham?

Air quality is satisfactory. Enjoy outdoor activities. The UV Index is 12.9 (Extreme).

Air Quality in Waltham, United States

Windy

34.1°C · 43.2% humidity

34.1°

Feels 37.7°

Good

Air quality is satisfactory. Enjoy outdoor activities.

4 stations

Nearby Monitoring Stations

AQI Forecast Calibrated

5 10am

18 1pm

9 4pm

7 7pm

6 10pm

5 1am

5 4am

5 7am

Station readings

CAMS model adj -20

Air Quality Index Trend

46h · 1 stn

View full history →

Waltham's air quality is primarily affected by vehicle emissions and industrial activity. Seasonal wildfire smoke and weather patterns can cause periodic air quality deterioration.

43.2%

Humidity

61.4 km/h

Wind WSW

1013.0 hPa

Pressure

12.9

UV Extreme

GoodModerateUSGUnhealthyVery UnhealthyHazardous

Which pollutant is driving the AQI?

PM2.5▲

4.33 µg/m³

PM10

13.7 µg/m³

050100150200300500

What is the weather forecast for Waltham?

Temperature & Precipitation

PM2.5 Trend

46h · 1 station

PM2.54.33 µg/m³ ✓ WHO

Good

PM1013.7 µg/m³

Good

UV INDEX12.9

Extreme

Station readings (4 stations within 25 km)

4.33

Median

4.1

Average

0.8

Low

6.5

High

PM2.5 µg/m³ · Model: 5.8 · Bias: +1.5

Both models agree Avg diff: 4.7°C

Where are air quality stations near Waltham?

Boston Roxbury

13.6 km PM2.5: 4.8 µg/m³

Boston Roxbury

13.6 km PM2.5: 5.0 µg/m³

Boston

14.6 km PM2.5: 5.0 µg/m³

East Dedham

15.6 km 69.8°C 71.0% RH PM2.5: 0.7 µg/m³ PM10: 1.2 µg/m³

Lynn Water Treatment Plant

24.3 km PM2.5: 4.8 µg/m³

Lynn Water Treatment Plant

24.3 km PM2.5: 5.0 µg/m³

What cities are near Waltham?

20 Watertown 20 Belmont 20 Brighton 18 Chestnut Hill 23 Allston 13 Wellesley 10 Needham 22 Brookline 24 Cambridge 24 Somerville

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ModerateAQI > 50 Unhealthy for Sensitive GroupsAQI > 100 UnhealthyAQI > 150 Very UnhealthyAQI > 200

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Data sources: AQI from ground-level monitoring stations via AQICN. Weather forecast from ECMWF (IFS & CAMS models). AQI calculated using US EPA standard. Updated 2026-09-05T17:11 UTC.