Doppler temperatures have been obtained in the mesopause region (85 km) above Bear Lake Observatory, Utah, over a period of two years, using the hydroxyl (OH) emission. The mid-latitude mesopause temperature decreases 60 K from a winter maximum of 220 K to a summer minimum of 160 K. ‘Sudden Mesopause Cooling’ Events of 30 K amplitude have been observed during mid-winter, one in January 1994 and two in January / February 1995, which appear to be associated with ‘stratospheric sudden warming’ phenomena. Tidal variations in temperature can be observed by taking hourly averages of data over a one-month period. The largest tidal amplitudes, of 10 – 20 K, occur during winter, while amplitudes in summer are smaller, 2 K.