Spatial and temporal variability in minimum temperature trends in the western U.S. sagebrush steppe

• We analyzed 65–125 yrs of minimum temperature data for sites in the Western US.
• Winters were the most variable season year-over-year.
• There were decadal trends in both directions (hotter and colder).
• The 10 sites we analyzed acted independently, with few common patterns.

Climate is a major driver of ecosystem dynamics. In recent years there has been considerable interest in future climate change and potential impacts on ecosystems and management options. In this paper, we analyzed minimum monthly temperature (T min) for ten rural locations in the western U.S. sagebrush steppe. Oregon and Nevada each had five locations, and the period of record ranged from 69 to 125 years. We used structural time series analysis to evaluate trends over time at each location. We also used box plots to compare variation within months at each location. We concluded: 1) T min variation over years is much higher during the winter than during other seasons, 2) there is evidence of decadal trends in both directions (hotter and cooler) for most, but not all sites, and 3) sites exhibited individualistic patterns rather than following a general regional pattern. The analysis shows that sites in relatively close proximity can exhibit different temperature patterns over time. We suggest that ecologists and land managers make use of any available weather data from local weather stations when planning for the future or interpreting past changes in plant and animal populations, rather than relying on regional averages.