There has been an observed increase in surface temperatures of Central California since 1900. To better understand this observation, daily TMax and TMin data have been accessed from every station available, some from original records and digitized, to more than triple the stations now used in gross assessments of climate trends. Station metadata from over 2000 forms were also examined to determine breakpoints in each station's time series. A method was applied to generate a grouped time series from the homogeneous segments of all stations in a category. Stations were grouped into a) irrigated valley b) foothills and c) mountains. Preliminary results show only one time series displays significant warming (highly significant) - TMin for irrigated valley stations. Other time series indicate no warming (or cooling) that would likely be related to other anthropogenic sources (i.e. greenhouse gases).