This WWW page provides several climatologies derived from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS).
I usually use the period 1950-79 for climatologies as there is relatively good sampling and relatively little decadal variability during this period. A 1900-79 SST climatology is also provided. Up until recently ICOADS was only available in 2-degree latitude-longitude resolution. One-degree latitude-longitude data is now available, and an SST climatology based on this data for 1960-79 is also provided. The 1-degree data begins in 1960 at this time. For each climatology, the contribution of each month and year to the climatology is weighted by the number of observations in that month and year. All observations are used.
The annual mean for the two SST climatologies are shown below to indicate the coverage of each climatology. Shading indicates regions with climatological values for all calendar months. The high-latitude oceans may have climatological values only for their summers.
Data in netCDF format:
At JISAO: /home/disk/margaret2/jisao/data_sets/coads_climatologies/
1950-79 climatologies (~0.4 Mb)