Hourly Weather | Today Saturday, September 19, 2026
Waltham, Massachusetts
1 AM
Cloudy Weather
48°
Feels Like 48°
0
Humidity: 84%
UV Index: 0
Wind: 5 mph
2 AM
Cloudy Weather
48°
Feels Like 48°
0
Humidity: 86%
UV Index: 0
Wind: 5 mph
3 AM
Cloudy Weather
48°
Feels Like 46°
0
Humidity: 87%
UV Index: 0
Wind: 5 mph
4 AM
Cloudy Weather
46°
Feels Like 45°
0
Humidity: 93%
UV Index: 0
Wind: 5 mph
5 AM
Cloudy Weather
48°
Feels Like 46°
0
Humidity: 88%
UV Index: 0
Wind: 6 mph
6 AM
Cloudy Weather
48°
Feels Like 46°
0
Humidity: 88%
UV Index: 0
Wind: 6 mph
7 AM
Cloudy Weather
50°
Feels Like 48°
0
Humidity: 86%
UV Index: 0
Wind: 6 mph
8 AM
Cloudy Weather
54°
Feels Like 52°
7
Humidity: 81%
UV Index: 0
Wind: 6 mph
9 AM
Cloudy Weather
55°
Feels Like 55°
7
Humidity: 74%
UV Index: 1
Wind: 7 mph
10 AM
Cloudy Weather
59°
Feels Like 57°
7
Humidity: 69%
UV Index: 1
Wind: 7 mph
11 AM
Cloudy Weather
61°
Feels Like 61°
7
Humidity: 63%
UV Index: 1
Wind: 8 mph
12 PM
Cloudy Weather
63°
Feels Like 63°
7
Humidity: 60%
UV Index: 1
Wind: 9 mph
1 PM
Cloudy Weather
63°
Feels Like 61°
11
Humidity: 65%
UV Index: 1
Wind: 10 mph
2 PM
Rainy Weather
63°
Feels Like 57°
72
Humidity: 70%
UV Index: 1
Wind: 12 mph
3 PM
Rainy Weather
63°
Feels Like 55°
72
Humidity: 74%
UV Index: 1
Wind: 13 mph
4 PM
Rainy Weather
61°
Feels Like 54°
72
Humidity: 78%
UV Index: 1
Wind: 13 mph
5 PM
Cloudy Weather
61°
Feels Like 55°
49
Humidity: 84%
UV Index: 0
Wind: 14 mph
6 PM
Cloudy Weather
61°
Feels Like 55°
49
Humidity: 87%
UV Index: 0
Wind: 14 mph
7 PM
Rainy Weather
61°
Feels Like 52°
57
Humidity: 89%
UV Index: 0
Wind: 13 mph
8 PM
Rainy Weather
61°
Feels Like 52°
79
Humidity: 91%
UV Index: 0
Wind: 12 mph
9 PM
Rainy Weather
61°
Feels Like 54°
79
Humidity: 92%
UV Index: 0
Wind: 10 mph
10 PM
Rainy Weather
59°
Feels Like 54°
79
Humidity: 93%
UV Index: 0
Wind: 8 mph
11 PM
Rainy Weather
59°
Feels Like 54°
76
Humidity: 94%
UV Index: 0
Wind: 7 mph

Hourly Air Quality Forecast - AQI (US EPA)

1 AM
31 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.76 µg/m³
  • PM10: 2.45 µg/m³
  • O3: 0.034 ppm
  • NO2: 2.1 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

2 AM
33 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.8 µg/m³
  • PM10: 2.55 µg/m³
  • O3: 0.035 ppm
  • NO2: 1.7 ppb
  • SO2: 0.3 ppb
  • CO: 0.16 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

3 AM
33 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.77 µg/m³
  • PM10: 2.52 µg/m³
  • O3: 0.036 ppm
  • NO2: 1.4 ppb
  • SO2: 0.3 ppb
  • CO: 0.16 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

4 AM
33 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.78 µg/m³
  • PM10: 2.57 µg/m³
  • O3: 0.035 ppm
  • NO2: 1.4 ppb
  • SO2: 0.4 ppb
  • CO: 0.16 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

5 AM
31 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.84 µg/m³
  • PM10: 2.65 µg/m³
  • O3: 0.033 ppm
  • NO2: 1.5 ppb
  • SO2: 0.4 ppb
  • CO: 0.17 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

6 AM
28 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.78 µg/m³
  • PM10: 2.59 µg/m³
  • O3: 0.031 ppm
  • NO2: 1.6 ppb
  • SO2: 0.4 ppb
  • CO: 0.17 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

7 AM
26 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.59 µg/m³
  • PM10: 2.38 µg/m³
  • O3: 0.028 ppm
  • NO2: 1.8 ppb
  • SO2: 0.4 ppb
  • CO: 0.17 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

8 AM
25 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.34 µg/m³
  • PM10: 2.1 µg/m³
  • O3: 0.026 ppm
  • NO2: 2.1 ppb
  • SO2: 0.4 ppb
  • CO: 0.17 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

9 AM
24 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.07 µg/m³
  • PM10: 1.79 µg/m³
  • O3: 0.026 ppm
  • NO2: 2.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.17 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

10 AM
24 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 0.84 µg/m³
  • PM10: 1.52 µg/m³
  • O3: 0.026 ppm
  • NO2: 2.1 ppb
  • SO2: 0.3 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

11 AM
25 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 0.73 µg/m³
  • PM10: 1.38 µg/m³
  • O3: 0.027 ppm
  • NO2: 1.9 ppb
  • SO2: 0.4 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

12 PM
27 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 0.68 µg/m³
  • PM10: 1.29 µg/m³
  • O3: 0.029 ppm
  • NO2: 1.6 ppb
  • SO2: 0.4 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

1 PM
29 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 0.84 µg/m³
  • PM10: 1.43 µg/m³
  • O3: 0.032 ppm
  • NO2: 1.4 ppb
  • SO2: 0.4 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

2 PM
32 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.17 µg/m³
  • PM10: 1.75 µg/m³
  • O3: 0.034 ppm
  • NO2: 1.1 ppb
  • SO2: 0.4 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

3 PM
35 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.62 µg/m³
  • PM10: 2.19 µg/m³
  • O3: 0.038 ppm
  • NO2: 0.8 ppb
  • SO2: 0.4 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

4 PM
38 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.96 µg/m³
  • PM10: 2.53 µg/m³
  • O3: 0.041 ppm
  • NO2: 0.7 ppb
  • SO2: 0.3 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

5 PM
39 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.08 µg/m³
  • PM10: 2.67 µg/m³
  • O3: 0.042 ppm
  • NO2: 0.6 ppb
  • SO2: 0.3 ppb
  • CO: 0.18 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

6 PM
37 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.07 µg/m³
  • PM10: 2.73 µg/m³
  • O3: 0.040 ppm
  • NO2: 1.1 ppb
  • SO2: 0.3 ppb
  • CO: 0.19 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

7 PM
33 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.97 µg/m³
  • PM10: 2.75 µg/m³
  • O3: 0.035 ppm
  • NO2: 1.9 ppb
  • SO2: 0.3 ppb
  • CO: 0.19 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

8 PM
30 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.8 µg/m³
  • PM10: 2.74 µg/m³
  • O3: 0.032 ppm
  • NO2: 2.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.19 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

9 PM
28 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.56 µg/m³
  • PM10: 2.68 µg/m³
  • O3: 0.031 ppm
  • NO2: 2 ppb
  • SO2: 0.2 ppb
  • CO: 0.19 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

10 PM
28 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.35 µg/m³
  • PM10: 2.63 µg/m³
  • O3: 0.030 ppm
  • NO2: 1.6 ppb
  • SO2: 0.2 ppb
  • CO: 0.19 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

11 PM
27 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.2 µg/m³
  • PM10: 2.62 µg/m³
  • O3: 0.029 ppm
  • NO2: 1.3 ppb
  • SO2: 0.2 ppb
  • CO: 0.19 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.