Air Quality
Maine recorded a 2023 average PM2.5 level around 5.5 micrograms per cubic meter, among the cleanest air in the eastern U.S., though summer wildfire smoke has occasionally raised levels.
Monitored days with good air quality
1990–2025U.S. EPA AirData, Annual AQI by County, all monitored Maine counties.
Monitored days unhealthy for sensitive groups or worse
1990–2025U.S. EPA AirData, Annual AQI by County (AQI above 100).
| Indicator | Maine | U.S. |
|---|---|---|
| Average PM2.5 (ug/m3) | 5.5 | 8 |
- •Canadian wildfire smoke pushed Maine's air quality index into unhealthy ranges briefly in June 2023.
Wildfires
Maine recorded roughly 450 wildfires burning about 500 acres in 2023, a small total reflecting the state's humid climate and active forest fire prevention program.
| Indicator | Maine | U.S. |
|---|---|---|
| Acres burned by wildfire (thousands) | 0.5 | 2600 |
- •Nearly all of Maine's wildfires are human-caused, mostly from unpermitted debris burning.
Drought
About 12% of Maine was classified in moderate or worse drought in late 2023, a level far below the persistent drought conditions seen in much of the western U.S.
Area in drought (D1–D4), yearly average
2000–2025U.S. Drought Monitor (NDMC / USDA / NOAA), average of weekly maps.
Area in extreme or exceptional drought (D3–D4)
2000–2025U.S. Drought Monitor (NDMC / USDA / NOAA), average of weekly maps.
| Indicator | Maine | U.S. |
|---|---|---|
| Land area in drought late 2023 (%) | 12 | 24 |
- •In 2022, nearly 90% of Maine was under some level of drought at its peak, an unusually severe event for the state.
Water Usage
Maine withdrew roughly 130 million gallons per day of freshwater for public supply and industry in 2020, one of the lowest totals per capita among states due to abundant surface water.
| Indicator | Maine | U.S. |
|---|---|---|
| Public supply withdrawal (billion gallons/day) | 0.13 | 39 |
- •Maine has over 6,000 lakes and ponds, supporting relatively low per-capita water stress.
Emissions
Maine emitted about 15.6 million metric tons of energy-related CO2 in 2022, among the lowest totals of any state due to its clean electricity mix and small population.
Energy-related CO₂ emissions
1970–2021U.S. EIA State Energy Data System, all sectors and fuels (FRED EMISSCO2TOTVTTTOMEA).
Transportation CO₂ emissions
1970–2021U.S. EIA State Energy Data System, transportation sector (FRED EMISSCO2TOTVTCTOMEA).
| Indicator | Maine | U.S. |
|---|---|---|
| CO2 emissions (million metric tons) | 15.6 | 4900 |
- •Maine has cut energy-related CO2 emissions by about 30% since 2005.
Climate Indicators
Maine's statewide average temperature has risen about 3.2°F since 1900, faster than the U.S. average, with 2023 among its warmest years on record.
Average annual temperature
1895–2025NOAA National Centers for Environmental Information, Climate at a Glance, statewide January–December average.
Annual precipitation
1895–2025NOAA National Centers for Environmental Information, Climate at a Glance, statewide January–December total.
| Indicator | Maine | U.S. |
|---|---|---|
| Temperature rise since 1900 (F) | 3.2 | 2.5 |
- •The Gulf of Maine is warming faster than about 96% of the world's oceans.