Last updated: September 10, 2025
Article
Climate Monitoring at Sand Creek Massacre National Historic Site: Water Year 2024
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Overview
Together, climate and hydrology shape ecosystems and the services they provide, particularly in arid and semi-arid ecosystems and across the Southern Plains (Woodhouse and Overpeck 1998). Understanding changes in climate, groundwater, and surface water is key to assessing the condition of park natural resources—and often, cultural resources.
At Sand Creek Massacre National Historic Site (Figure 1), Southern Plains Inventory and Monitoring Network scientists study how ecosystems may be changing by taking measurements of key resources, or “vital signs,” year after year—much as a doctor keeps track of a patient’s vital signs. This long-term ecological monitoring provides early warning of potential problems, allowing managers to mitigate them before they become worse. At Sand Creek Massacre National Historic Site, we monitor climate among other vital signs.
Reporting is by water year (WY), which begins in October of the previous calendar year and goes through September of the water year (e.g., WY2024 runs from October 2023 through September 2024). This web report presents the results of climate monitoring at Sand Creek Massacre National Historic Site in WY2024.
Reference: Woodhouse, C. A., and J. T. Overpeck. 1998. 2000 years of drought variability in the central United States. Bulletin of the American Meteorological Society 79(12): 2693–2714. https://doi.org/10.1175/1520-0477(1998)079%3C2693:YODVIT%3E2.0.CO;2
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Climate and Weather
There is often confusion over the terms, “weather” and “climate.” In short, weather describes instantaneous meteorological conditions (e.g., it’s currently raining or snowing, it’s a hot or frigid day), and climate reflects patterns of weather at a given place over longer periods of time (seasons to years). Climate is the primary driver of ecological processes on earth. Climate and weather information provide context for understanding the status or condition of other park resources.
Methods
A National Oceanic and Atmospheric Administration Cooperative Observer Program (NOAA COOP) weather station (Eads #052446) has been operational 15.5 mi (24.9 km) southwest of Sand Creek Massacre National Historic Site since 1907 (Figure 1). This station provides a reliable, long-term climate dataset used for analyses in this report. Data from this station are accessible through Climate Analyzer.
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Results
Precipitation
Annual precipitation at the weather station southwest of Sand Creek Massacre National Historic Site in WY2024 was 10.23″ (26.0 cm), 5.47″ (13.9 cm) less than the 1991–2020 annual average. Nine months in WY2024 received less precipitation than the 1991–2020 averages (Figure 2). No precipitation was registered at the weather station in November and March. December, February, and May received 59–98% more precipitation than average, but these surpluses did not make up for the precipitation deficit accumulated over the rest of the year. Extreme daily rainfall events (≥ 1.00″, 2.54 cm) occurred on 1 day, less than the average annual frequency of 2.7 days. The single extreme rainfall event occurred on 29 May 2024 (2.00″, 5.1 cm).
Air Temperature
The mean annual maximum temperature at the weather station southwest of Sand Creek Massacre National Historic Site in WY2024 was 70.7°F (21.5°C), 3.4°F (1.9°C) above the 1991–2020 average. The mean annual minimum temperature in WY2024 was 39.4°F (4.1°C), 1.9°F (1.1°C) above the 1991–2020 average. Mean monthly maximum and minimum temperatures in WY2024 differed by as much as 6.9°F (3.8°C; see February as an example) relative to the 1991–2020 monthly averages (Figure 2). Mean monthly maximum temperatures were above average in every month except January. Mean monthly minimum temperatures were above average in nine months and slightly below average in three months (January, March, and July). Extremely hot temperatures (≥ 96.0°F; 35.6°C) occurred on 37 days in WY2024, over 50% more than the average frequency of 23.3 days. Extremely cold temperatures (≤ 10.0°F, −12.2°C) occurred on 14 days, a third less than the average frequency of 20.7 days.
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Drought
Reconnaissance drought index (Tsakiris and Vangelis 2005) provides a measure of drought severity and extent relative to the long-term climate. It is based on the ratio of average precipitation to average potential evapotranspiration (the amount of water loss that would occur from evaporation and plant transpiration if the water supply was unlimited) over short periods of time (seasons to years). The reconnaissance drought index for Sand Creek Massacre National Historic Site indicates that WY2024 was drier than the 1991–2024 average from the perspective of both precipitation and potential evapotranspiration (Figure 3).
Reference: Tsakiris G., and H. Vangelis. 2005. Establishing a drought index incorporating evapotranspiration. European Water 9: 3–11.
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Report Citation
Authors: Kara Raymond, Andy Ray
Raymond, K., and A. Ray. 2025. Climate and Weather Monitoring at Sand Creek Massacre National Historic Site: Water Year 2024. Southern Plains Network, National Park Service, Pecos, New Mexico.