Hourly Weather | Today Wednesday, May 20, 2026
Active Weather Warnings
Somerville, Massachusetts
7 PM
Stormy Weather
82°
Feels Like 79°
51
Humidity: 44%
UV Index: 0
Wind: 16 mph
8 PM
Cloudy Weather
81°
Feels Like 75°
25
Humidity: 44%
UV Index: 0
Wind: 13 mph
9 PM
Cloudy Night
77°
Feels Like 73°
20
Humidity: 47%
UV Index: 0
Wind: 12 mph
10 PM
Cloudy Night
73°
Feels Like 72°
20
Humidity: 49%
UV Index: 0
Wind: 12 mph
11 PM
Cloudy Night
72°
Feels Like 70°
20
Humidity: 51%
UV Index: 0
Wind: 10 mph

Hourly Air Quality Forecast - AQI (US EPA)

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

Pollutant Concentrations:

  • PM2.5: 7.28 µg/m³
  • PM10: 10.28 µg/m³
  • O3: 0.045 ppm
  • NO2: 2.4 ppb
  • SO2: 0.3 ppb
  • CO: 0.13 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.76 µg/m³
  • PM10: 8.98 µg/m³
  • O3: 0.041 ppm
  • NO2: 3.1 ppb
  • SO2: 0.3 ppb
  • CO: 0.14 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.06 µg/m³
  • PM10: 7.54 µg/m³
  • O3: 0.038 ppm
  • NO2: 3.3 ppb
  • SO2: 0.3 ppb
  • CO: 0.14 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 5.12 µg/m³
  • PM10: 6.13 µg/m³
  • O3: 0.034 ppm
  • NO2: 3.3 ppb
  • SO2: 0.3 ppb
  • CO: 0.14 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.91 µg/m³
  • PM10: 4.65 µg/m³
  • O3: 0.032 ppm
  • NO2: 3.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.14 ppm

Health Recommendations:

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

Weather Alerts and Warnings for Somerville

Moderate Expected Likely

Heat Advisory

Heat Advisory issued May 20 at 9:33AM EDT until May 20 at 8:00PM EDT by NWS Boston/Norton MA
May 20, 9:33 AM May 20, 8:00 PM
WHAT: Heat index values up to 96.

WHERE: Portions of northern Connecticut, central, eastern,
northeastern, southeastern, and western Massachusetts, and
northern Rhode Island.

WHEN: Until 8 PM EDT this evening.

IMPACTS: Hot temperatures and high humidity may cause heat
illnesses.
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Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke.
Updated: May 20, 6:08 PM Source: NWS Alert