Air Quality and Weather

Snow covered maplesVermont’s weather is characterized by a high degree of variability. Air masses originating from the northwest, west, and south shape our weather and are key factors in our weather fluctuations. Vermont’s mountainous terrain creates site-specific differences in weather and compounds the complexity of weather forecasting.

In describing atmospheric conditions, weather is defined in short time frames that can range from minutes to about a week. In short, weather is experienced on a daily basis. Climate, on the other hand, refers to long-term trends and averages in atmospheric variables, with a time frame that can range from months or years to millennia.

Forests can moderate temperatures and moisture. Forest climate monitoring provides additional insight into how temperature and precipitation changes are affecting forest ecosystems in Vermont.

Over the past few decades, we have observed changes in Vermont climate variables. Some examples are the long-term (30-year) averages for winter temperatures, which are no longer as cold; summer temperatures that are now warmer than usual; and an increased number of frost-free days. And signs of these climate change impacts have been observed in our forests.

Vermont’s forests have been historically adapted to a climate abundant in moisture, with snowy winters and moderately warm summers. When conditions differ from any long-term averages, there are impacts to the trees, seedlings, plants on the forest floor, and the many organisms that rely on forests as their home.

Air quality in Vermont has improved over the past few decades thanks in part to the 1977 Clean Air Act. Some airborne pollutants are generated in Vermont or our region, while others have been transported from thousands of miles away. Pollutants can be deposited as wet deposition, dissolved in rain, snow or cloud water, or as dry deposition adhering to plant leaves or onto water surfaces. Ozone pollution affects tree leaves when these molecules enter leaf pores, disrupting cells and cell functions.

Vermont Weather and Climate

Forest Climate Monitoring

Air Quality

Acid Deposition

Critical Loads



Carbon dioxide and greenhouse gases

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