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Upper Delaware Scenic and Recreational River in 2021: a very warm, wet year
In 2021 the area around Upper Delaware Scenic and Recreational River, on the Pennsylvania and New York border, was very warm and wet. The year ended as the 5th warmest and 23rd wettest on record. Over the long term, annual average temperature and annual total precipitation have both increased.
Canoes on the shore of the Delaware River. NPS photo.
Where the numbers come from
The Eastern Rivers and Mountains Network measures ecosystem "vital signs" in selected national parks in West Virginia, Pennsylvania, New Jersey and New York, and weather and climate is one of them. This summary uses county-scale data averaged over the counties around the park: Pike and Wayne counties in Pennsylvania, and Delaware, Orange and Sullivan counties in New York, for 1895 to 2021 (the period of record). 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
In total, 2021 was the 5th warmest year on record for the park's counties, with an annual average of 48.7 °F, 2.8 °F above the long-term average. Ten months were warmer than normal; October (+6.7 °F) and December (+7.9 °F) stood out, and May and November were slightly cooler than normal.
| Month or year | Average temperature (°F) | Departure from long-term average (°F) |
|---|---|---|
| January | 25.9 | +3.5 |
| February | 24.4 | +0.8 |
| March | 36.4 | +3.7 |
| April | 46.6 | +2.1 |
| May | 55.2 | -0.2 |
| June | 66.4 | +2.5 |
| July | 69.2 | +0.6 |
| August | 70.1 | +3.6 |
| September | 62.3 | +2.7 |
| October | 55.5 | +6.7 |
| November | 37.5 | -0.2 |
| December | 34.7 | +7.9 |
| 2021 | 48.7 | +2.8 |
Departures show how 2021 differed from the averages for 1895 to 2020.
Precipitation
The year was the 23rd wettest on record for these counties. In all, 50.84 inches fell, more than 6 inches above the long-term average. July (+3.30 in.), September (+4.28 in.) and October (+3.24 in.) were the months furthest above normal.
| Month or year | Total precipitation (in.) | Departure from long-term average (in.) |
|---|---|---|
| January | 1.89 | -1.18 |
| February | 3.29 | +0.47 |
| March | 2.48 | -0.95 |
| April | 2.67 | -1.08 |
| May | 4.95 | +0.96 |
| June | 2.56 | -1.68 |
| July | 7.64 | +3.30 |
| August | 5.78 | +1.53 |
| September | 8.24 | +4.28 |
| October | 6.99 | +3.24 |
| November | 2.48 | -1.06 |
| December | 1.86 | -1.58 |
| 2021 | 50.84 | +6.24 |
The long-term trend, 1895 to 2021
Annual average temperature has risen by about 0.22 °F per decade and annual total precipitation by about 0.47 inches per decade since 1895.
Annual average temperature (°F) and annual total precipitation (in.), 1895 to 2021. 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 3.2 to 9.5 °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, Eastern Rivers and Mountains Network, "2021 Weather In Review: Upper Delaware Scenic and Recreational River" (https://www.nps.gov/articles/000/2021-weather-in-review-upper-delaware-scenic-and-recreational-river.htm), published as a work of the United States government; the page's seasonal ranking charts and seasonal statements are left out because they do not agree with its monthly tables; rewritten in hubnx's own words.