2022 Weather in Review: Valley Forge National Historical Park

The National Memorial Arch at Valley Forge National Historical Park

Garen M. / Flickr (CC BY-NC 2.0)

In order to better understand ecosystem health in national parks, the Mid-Atlantic Inventory and Monitoring Network measures ecosystem "vital signs" across the Mid-Atlantic region. One of those vital signs is weather and climate. Below is a summary of 2022 weather conditions at Valley Forge National Historical Park.

This brief provides county-scale weather data averaged from all of the counties surrounding the park, including data from 1895–2022 (i.e., period of record). These counties include Chester and Montgomery counties, PA. Data and analyses herein are courtesy of the National Oceanic and Atmospheric Administration's (NOAA) Climate at a Glance Program.

Weather vs. Climate

First of all, what is the difference between weather and climate? Weather consists of the short-term (minutes to months) changes in the atmosphere. Weather is what is happening outside at this very moment, be it rain, snow, or just a warm sunny day. Climate is what you expect to see based on long-term patterns of over 30 years or more. An easy way to remember the difference is that climate is what you might expect, like a hot summer, and weather is what you get, like a warm rainy day.

The following information includes a discussion of 2022 weather placed in the context of long-term climate (i.e., how did 2022 compare to a "normal" year?).

2022 Summary

In all, 2022 was a very warm year but total precipitation was near normal. The year ended as the 15^th warmest and 59^th wettest on record. Data indicate that over the long term, annual average temperature and annual total precipitation have both increased in the counties surrounding the park (+0.2 °F per decade and +0.33 inches per decade, respectively).

Temperature

In total, 2022 was the 15^th warmest year ever recorded at the park with all seasons being warmer than normal (Figure 1). Ten months had higher than normal temperatures with February and August both being more than 4 °F above long-term averages (Table 1).

Figure 1. Seasonal and annual temperature rankings for park counties. An arrow at the top of the figure would represent the warmest year/season on record (since 1895); at the bottom, the coldest year/season on record. Winter = Jan–Mar, Spring = Apr–June, Summer = July–Sept, Autumn = Oct–Dec.

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_{Table 1. Monthly and annual average temperature and departure from long-term averages. Departures from average show how different 2022 was compared to relevant averages from 1895-2021.}

Month/Year	Average temperature (°F)	Departure from long-term average (°F)
January	28.2	−1.2
February	35.0	+4.2
March	43.6	+3.8
April	51.2	+0.7
May	63.5	+2.5
June	70.2	+0.6
July	77.9	+3.4
August	76.8	+4.4
September	67.2	+1.5
October	53.0	−1.2
November	46.8	+3.6
December	34.9	+1.8
2022	54.0	+2.0

Precipitation

The year was near normal for total precipitation, but spring and autumn were wet and summer and winter were dry. In all, it was the 59^th wettest year recorded at
the park (Figure 2), with 45.8 inches of total precipitation (Table 2).

Figure 2. Seasonal and annual precipitation rankings for park counties. An arrow at the top of the figure would represent the wettest year/season on record (since 1895); at the bottom, the driest year/season on record. Winter = Jan–Mar, Spring = Apr–June, Summer = July–Sept, Autumn = Oct–Dec.

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_{Table 2. Monthly and annual total precipitation and departure from long-term averages. Departures from average show how different 2022 was compared to relevant averages from 1895-2021.}

Month/Year	Total precipitation (in.)	Departure from long-term average (in.)
January	3.21	−0.21
February	2.71	−0.32
March	2.58	−1.21
April	5.92	+2.21
May	5.39	+1.44
June	3.76	−0.29
July	3.46	−1.14
August	2.57	−1.98
September	3.98	−0.01
October	5.62	+2.18
November	2.83	−0.53
December	4.83	+1.16
2022	46.87	+1.30

Temperature and Precipitation Trends
(1895-2022)

Data for Chester and Montgomery counties, PA indicate that annual average temperature has increased approximately +0.2 °F per decade and annual total precipitation has increased approximately +0.33 inches per decade since 1895 (Figure 3).

National Park Service scientists have forecast future changes in climate too. Models estimate that by 2100, annual average temperature at the park will increase by 3.1–9.0 °F (from a best-case to worst-case scenario, respectively). Annual total precipitation is expected to increase by 7–14% (see Gonzalez et al., 2018 for details).

Figure 3. Annual average temperature (°F) and annual total precipitation (in.) from 1895–2022 for Chester and Montgomery counties, PA. Dashed lines represent linear estimates of change.

Climate Change

Today's rapid climate change challenges national parks in ways we've never seen before. Wildlife migrations are altered, increasingly destructive storms threaten cultural resources and park facilities, habitat is disrupted—the list goes on. Go to the NPS Climate Change site to discover how climate change is affecting our nation's treasures, what the National Park Service is doing about it, and how you can help.

A summary of the Mid-Atlantic Network's weather and climate monitoring program can be found here. For more information, contact Mid-Atlantic Network Biologist, Jeb Wofford. Data included in this article were obtained from NOAA's NClimDiv dataset (version v1.0.0-20230106).

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