Hopewell Furnace National Historic Site in 2021: an extremely warm year

In 2021 the area around Hopewell Furnace National Historic Site, in Pennsylvania, was extremely warm, with near-normal total precipitation: the year ranked 61st wettest on record. Over the long term, annual average temperature and annual total precipitation have both increased.

Where the numbers come from

The Mid-Atlantic Inventory and Monitoring Network measures ecosystem "vital signs" across the Mid-Atlantic region, and weather and climate is one of them. This summary uses county-scale data averaged over the counties around the park, Berks and Chester counties in Pennsylvania. The data and analyses come from NOAA's Climate at a Glance program.

The page explains that weather is short-term (minutes to months) change in the atmosphere, what is happening outside at this very moment, while climate is what one expects from long-term patterns over 30 years or more: climate is what you might expect, like a hot summer, and weather is what you get, like a warm rainy day.

Temperature

The 2021 annual average was 54.5 °F, 3.2 °F above the long-term average. Eleven months were warmer than normal, and January, March, August, October and December were at least 4.0 °F above their long-term averages. The page gives the year's rank as the 4th warmest in its text and the 3rd warmest in its short description, so no rank is given here.

Departures show how 2021 differed from the averages for 1895 to 2020.

Precipitation

Total precipitation for 2021 was 45.35 inches, almost identical to the long-term average (+0.01 inches), and ranked 61st wettest on record. September was the wettest month relative to normal (+4.81 in.), and December (-2.50 in.) and November (-2.05 in.) the driest.

The long-term trend, 1895 to 2021

For Berks and Chester counties, annual average temperature has risen by about 0.21 °F per decade and annual total precipitation by about 0.38 inches per decade since 1895.

Annual average temperature (°F) and annual total precipitation (in.), 1895 to 2021, Berks and Chester counties. Dashed lines show linear estimates of change. Chart from the National Park Service's page.

National Park Service scientists have also looked ahead. Models estimate that by 2100 the park's annual average temperature will rise by 3.1 to 9.0 °F, from the best-case to the worst-case scenario, and annual total precipitation by 7 to 14 percent; the page points to a 2018 paper by Gonzalez and colleagues for details.

Sources

• National Park Service, Mid-Atlantic Inventory and Monitoring Network, "2021 Weather In Review: Hopewell Furnace National Historic Site" (https://www.nps.gov/articles/000/2021-weather-in-review-hopewell-furnace-national-historic-site.htm), published as a work of the United States government; the page's lead photograph (a Flickr photo under CC BY-SA), its seasonal ranking charts, its seasonal statements and its temperature rank (it gives two) are left out; rewritten in hubnx's own words.