Hourly Weather | Today Wednesday, March 18, 2026
Portland, Maine
8 AM
Cloudy Weather
21°
Feels Like
0
Humidity: 44%
UV Index: 1
Wind: 16 mph
9 AM
Cloudy Weather
23°
Feels Like 10°
0
Humidity: 41%
UV Index: 2
Wind: 15 mph
10 AM
Cloudy Weather
25°
Feels Like 14°
0
Humidity: 38%
UV Index: 3
Wind: 14 mph
11 AM
Cloudy Weather
27°
Feels Like 18°
0
Humidity: 35%
UV Index: 4
Wind: 13 mph
12 PM
Cloudy Weather
27°
Feels Like 21°
0
Humidity: 33%
UV Index: 4
Wind: 13 mph
1 PM
Cloudy Weather
28°
Feels Like 23°
0
Humidity: 31%
UV Index: 4
Wind: 13 mph
2 PM
Cloudy Weather
30°
Feels Like 28°
0
Humidity: 30%
UV Index: 4
Wind: 9 mph
3 PM
Cloudy Weather
30°
Feels Like 28°
0
Humidity: 30%
UV Index: 3
Wind: 9 mph
4 PM
Cloudy Weather
32°
Feels Like 28°
0
Humidity: 30%
UV Index: 2
Wind: 8 mph
5 PM
Cloudy Weather
30°
Feels Like 27°
0
Humidity: 32%
UV Index: 2
Wind: 8 mph
6 PM
Cloudy Weather
30°
Feels Like 25°
0
Humidity: 36%
UV Index: 1
Wind: 9 mph
7 PM
Cloudy Night
28°
Feels Like 21°
0
Humidity: 43%
UV Index: 0
Wind: 9 mph
8 PM
Cloudy Night
28°
Feels Like 19°
0
Humidity: 49%
UV Index: 0
Wind: 9 mph
9 PM
Cloudy Night
28°
Feels Like 21°
0
Humidity: 53%
UV Index: 0
Wind: 8 mph
10 PM
Cloudy Night
28°
Feels Like 21°
0
Humidity: 56%
UV Index: 0
Wind: 8 mph
11 PM
Cloudy Night
28°
Feels Like 21°
0
Humidity: 58%
UV Index: 0
Wind: 8 mph

Hourly Air Quality Forecast - AQI (US EPA)

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

Pollutant Concentrations:

  • PM2.5: 0.5 µg/m³
  • PM10: 0.9 µg/m³
  • O3: 0.052 ppm
  • NO2: 1.8 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 0.5 µg/m³
  • PM10: 0.91 µg/m³
  • O3: 0.052 ppm
  • NO2: 2 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 0.5 µg/m³
  • PM10: 0.97 µg/m³
  • O3: 0.052 ppm
  • NO2: 1.9 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 0.52 µg/m³
  • PM10: 1.07 µg/m³
  • O3: 0.052 ppm
  • NO2: 1.8 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 0.64 µg/m³
  • PM10: 1.22 µg/m³
  • O3: 0.052 ppm
  • NO2: 1.7 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 0.79 µg/m³
  • PM10: 1.37 µg/m³
  • O3: 0.054 ppm
  • NO2: 1.6 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 PM
51 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.01 µg/m³
  • PM10: 1.6 µg/m³
  • O3: 0.054 ppm
  • NO2: 1.6 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

3 PM
55 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.25 µg/m³
  • PM10: 1.88 µg/m³
  • O3: 0.056 ppm
  • NO2: 1.8 ppb
  • SO2: 0.4 ppb
  • CO: 0.15 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

4 PM
55 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.58 µg/m³
  • PM10: 2.28 µg/m³
  • O3: 0.056 ppm
  • NO2: 2.1 ppb
  • SO2: 0.4 ppb
  • CO: 0.15 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

5 PM
55 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 1.94 µg/m³
  • PM10: 2.74 µg/m³
  • O3: 0.056 ppm
  • NO2: 2.6 ppb
  • SO2: 0.5 ppb
  • CO: 0.15 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

6 PM
51 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.39 µg/m³
  • PM10: 3.39 µg/m³
  • O3: 0.054 ppm
  • NO2: 3.8 ppb
  • SO2: 0.6 ppb
  • CO: 0.16 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

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

Pollutant Concentrations:

  • PM2.5: 2.88 µg/m³
  • PM10: 4.17 µg/m³
  • O3: 0.052 ppm
  • NO2: 5.7 ppb
  • SO2: 0.8 ppb
  • CO: 0.17 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.3 µg/m³
  • PM10: 4.9 µg/m³
  • O3: 0.049 ppm
  • NO2: 6.7 ppb
  • SO2: 0.9 ppb
  • CO: 0.18 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.74 µg/m³
  • PM10: 5.56 µg/m³
  • O3: 0.048 ppm
  • NO2: 6.9 ppb
  • SO2: 0.9 ppb
  • CO: 0.18 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 4.15 µg/m³
  • PM10: 6.16 µg/m³
  • O3: 0.046 ppm
  • NO2: 6.9 ppb
  • SO2: 1 ppb
  • CO: 0.18 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 4.58 µg/m³
  • PM10: 6.78 µg/m³
  • O3: 0.045 ppm
  • NO2: 7 ppb
  • SO2: 1 ppb
  • CO: 0.19 ppm

Health Recommendations:

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