We, the staff, volunteers and associates of the Mohonk Preserve, have been collecting profiles of temperature data and Secchi depths in Mohonk Lake beginning in 1985. Mohonk Lake is small (6.9 ha), deep (zmax=18.5m), oligo-mesotrophic lake, dimictic, glacially formed system on the northern Shawangunk Ridge, New York State, USA. The temperature profiles can provide information on the lake thermal structure and can be used to calculate physical variables such as thermocline depth and thermal stability. We collected data weekly with two exceptions: 1) 01 Jan 1985 to 09 August 1985 when temperature profiles were collected daily and 2) in 2017, when temperature profiles were collected every 15 minutes and down-sampled to daily means.