To understand ecosystem health, the National Park Service's Mid-Atlantic Inventory and Monitoring Network measures "vital signs" in its parks, weather and climate among them. This is the summary for Valley Forge National Historical Park in 2023, using county-scale data averaged over Chester and Montgomery counties, Pennsylvania, with a record going back to 1895, from NOAA's Climate at a Glance program.
Valley Forge National Historical Park. NPS.
Weather or climate?
Weather is the short-term state of the atmosphere, from minutes to months — the rain, snow or sunshine outside right now. Climate is what you expect from patterns over 30 years or more. Put simply, climate is what you expect, like a hot summer; weather is what you get, like a warm rainy day.
2023 at a glance
2023 was extremely warm but close to normal for precipitation: the 4th warmest and 46th wettest year since records began in 1895.
Temperature
Winter and autumn were especially warm. Nine months were warmer than normal, and January, February and December were each more than 7.5°F above their long-term averages.
Seasonal and annual temperature rankings for the park's counties since 1895. Winter is January–March, spring April–June, summer July–September and autumn October–December. NPS.
| Month | Average (°F) | Departure from 1895–2022 average (°F) |
|---|---|---|
| January | 40.2 | +10.8 |
| February | 39.3 | +8.4 |
| March | 42.2 | +2.4 |
| April | 55.9 | +5.4 |
| May | 59.5 | −1.6 |
| June | 67.8 | −1.9 |
| July | 76.8 | +2.3 |
| August | 73.2 | +0.8 |
| September | 67.4 | +1.8 |
| October | 57.7 | +3.5 |
| November | 42.6 | −0.6 |
| December | 40.8 | +7.6 |
| Year | 55.2 | +3.2 |
Precipitation
Total precipitation was slightly above normal, at 47.52 inches, with a wet spring and autumn and a dry winter.
Seasonal and annual precipitation rankings for the park's counties since 1895. NPS.
| Month | Total (in.) | Departure from long-term average (in.) |
|---|---|---|
| January | 3.62 | +0.20 |
| February | 1.50 | −1.52 |
| March | 2.45 | −1.34 |
| April | 4.16 | +0.44 |
| May | 0.79 | −3.18 |
| June | 6.25 | +2.20 |
| July | 6.42 | +1.82 |
| August | 2.91 | −1.63 |
| September | 5.78 | +1.79 |
| October | 1.56 | −1.90 |
| November | 3.12 | −0.24 |
| December | 8.96 | +5.28 |
| Year | 47.52 | +1.94 |
The long-term trend
Since 1895, the park's counties have warmed by about 0.3°F per decade, and annual precipitation has risen by about 0.33 inches per decade. Park Service scientists project that by 2100 the park's average annual temperature will rise by 3.1–9.0°F, from the best case to the worst, and annual precipitation by 7–14% (Gonzalez and others, 2018).
Annual average temperature and total precipitation for Chester and Montgomery counties, 1895–2023; dashed lines show the linear trends. NPS.
Rapid climate change is challenging national parks in new ways — altering wildlife migrations, threatening cultural resources and facilities with more destructive storms, and disrupting habitat.
Sources
- National Park Service, Mid-Atlantic Inventory and Monitoring Network: "2023 Weather in Review: Valley Forge National Historical Park," using NOAA's nClimDiv dataset. The precipitation table's caption refers to 2022 and a 1895–2021 baseline, apparently carried over from the previous year's report, so the baseline years are not given for it here.
In these publicationsValley Forge National Historical Park
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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