Meteorology

Weather plays a major role in short term air quality concentrations and long term air quality trends. Climatological data from the National Weather Service (NWS) stations in Gray , ME and Caribou, ME are frequently used to interpret and evaluate air quality data and to forecast air quality levels in the near future. Temperatures and wind speeds are important as well as the number of days with a maximum temperature greater than 90 F. Precipitation data, in the equivalent inches of water, and the number of days with precipitation greater than 0.01 inches can also be useful in evaluating the potential for deposition of air pollutants. Heating degree days, which are derived by subtracting the average daily temperature from 65 F and keeping a running total for the year, can also be helpful in evaluating trends in air quality.

The Gray NWS station is located on a hill near the North Yarmouth border approximately 11 miles east of Sebago Lake in Cumberland County . There are trees to the southeast of the office, but much of the remainder of the area is open with a view of the nearby countryside. This new location is approximately 18 miles north of its former location at the Portland Jetport.

The Caribou NWS station is located at the Caribou Municipal Airport in Aroostook County . The airport lies on top of high land, which is approximately on the same level as the surrounding hills. The Aroostook River is located 1 mile to the east/southeast of the airport.

The Bureau also operates a number of meteorological sites, primarily for wind speed and direction information but also collect temperature, relative humidity and total solar at some of the sites. Currently there are eight sites that operate either annually or seasonally to support the ambient air monitoring program in the state. Monitors are located in Cape Elizabeth , Owls Head, Auburn , Augusta , two sites in Bar Harbor, Bangor and Presque Isle. In addition, there are tribal operated sites in Old Town , Perry and Presque Isle. Current data from all except the Presque Isle tribal site can be viewed at the air quality web site . Climatological data summaries from Gray and Caribou as well as annual wind roses can be viewed in the latest annual air quality report .