The Climate of Niwot Ridge, Front Range, Colorado, U.S.A.

The climate of Niwot Ridge is described using monthly and annual mean temperatures and monthly and annual total precipitation values for the period 1951 to 1985 and comparable precipitation values for the nearby Silver Lake station from 1915. Summary statistics and water budget values are presented. Time series analysis indicates abnormally low temperatures in the early 1980s and an overall downward trend in temperature. Autoregressive moving average forecasting models and spectral analysis hint at some cyclicity in the data series of annual values of both temperature and precipitation. Silver Lake annual precipitation data show only a slight downward trend when the extremely high value for the year of 1921 is excluded. Implications of these changes for the alpine tundra ecosystem are briefly discussed.