In Liverpool Bay (UK), suspended particulate matter (SPM) monitoring data and tidal data collected in the period September 2004 to February 2006 were analyzed by means of entropy analysis and factor analysis in order to identify the meteorological and oceanographic variables of importance for the characterisation of the shape of SPM size spectra. Entropy analysis of in situ particle size spectra revealed five basic types, each attributable to different sets of environmental conditions. The results of correlation analysis showed that changes in the position of the main modal are significantly related to several environmental variables. One important class of these relationships is represented by wave-related variables (e.g. wave energy, maximum orbital velocity). Another important class of correlations (e.g. with salinity, density, water depth) can be associated with the inshore-offshore gradient in depth and physicochemical conditions existing in the bay. The strongest correlations, however, were with the air and water temperatures. Factor analysis (with Varimax rotation) of the overall dataset extracted four factors, together explaining over 70% of variance. Factor 1 explains > 21% of the total variance, and appears to be related to wave activity. Factor 2, explaining 18.5% of the total variance, appears to be related to tidal currents. Factor 3 explains 16.4% of the total variance observed, and appears to be related to temperature-modulated seasonal differences in oceanographic conditions. Factor 4 explains 15.2% of the total variance observed, and represents the inshore-offshore gradient in depth and physicochemical conditions. These findings are a step towards a better characterisation of floc size and, therefore, more precise calculations of sedimentation and transport rates needed for an improved understanding of ecosystem functioning in Liverpool Bay and, for that matter, other similar settings.