2022 Weather in Review: Gettysburg National Military Park and Eisenhower National Historic Site

NPS photo

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 in Gettysburg National Military Park and Eisenhower National Historic Site.

This brief provides county-scale weather data for Adams County, PA, including data from 1895–2022 (i.e., period of record). 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 warm year with precipitation that was near normal. The year ended as the 22^nd warmest and 64^th wettest on record (since 1895) for Adams County, PA. Data indicate that over the long term, annual average temperature and annual total precipitation have both increased (+0.2 °F per decade and +0.27 inches per decade, respectively).

Temperature

In total, 2022 was the 22^nd warmest year at the parks since 1895 with all seasons being warmer than normal (Figure 1). Nine months had higher than normal temperatures with February, March, August, and November all being more than 3 °F above long-term averages (Table 1).

Figure 1. Seasonal and annual temperature rankings for Adams County, PA. 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	26.8	−2.0
February	34.5	+4.1
March	42.9	+3.2
April	50.0	−0.3
May	62.8	+2.1
June	70.4	+1.3
July	75.5	+1.8
August	74.8	+3.2
September	66.0	+1.2
October	51.9	−1.7
November	45.7	+3.4
December	33.4	+1.1
2022	52.9	+1.5

Precipitation

Total precipitation in 2022 was near normal (i.e. 64^th wettest year recorded; Figure 2) though the winter was very dry. Across the entire year the county received 0.16 inches less than the long-term average (Table 2).

Figure 2. Seasonal and annual precipitation rankings for Adams County, PA. 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	2.48	−0.60
February	2.91	+0.09
March	1.88	−1.74
April	3.59	+0.04
May	6.20	+2.19
June	3.04	−0.96
July	3.93	−0.04
August	3.59	−0.35
September	3.87	+0.01
October	3.11	−0.33
November	3.17	+0.09
December	4.66	+1.42
2022	42.43	−0.16

Temperature and Precipitation Trends
(1895-2022)

Data for Adams County, PA indicate that annual average temperature has increased
approximately +0.2 °F per decade and annual total precipitation has increased approximately +0.27 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 3.1–9.2 °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.) for Adams County, PA, from 1895–2022. 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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