A challenging night to begin observing campaign 22. Partly cloudy to nearly clear conditions for the first half of the night. Seeing was generally pretty poor (1.5-2.5 arcsec) and photometry was difficult due to clouds quickly forming and dissipating over the mountain. Just after midnight, the clouds thickened and the humidity rose rapidly to nearly dangerous levels, forcing a stop to observing. Fog rolled in at 0100 local time and stayed the rest of the night. All of this activity was caused by a strong cold front moving through Arizona that is forecast to drop the high temperature by over 10 degrees over yesterday's high.