(1) The prevalence of wasting is more seasonal than the prevalence of stuntedness (the outcome of stunting and some intra-uterine growth retardation and other processes). This is because stuntedness does not tend to be correctable after the age of about 24 months until the pre-adolescence growth spurt. We do not, therefore, expect the prevalence of stuntedness to change much over short periods of time. Stunting (the process) may be seasonal. We see growth faltering as a response to disease or poor nutrition (also seasonal). This will not always result in stuntedness to HAZ < -2 but it is stunting. I think you should be OK assessing the prevalence of stuntedness (stunting can only be detected by repeated measures). You may want to look at prevalence in 6-23 month and 24-59 month age-groups separately. (2) In some settings the DSS will vary by season but in others we might see DDS sustained but with different seasonal contributors (e.g. fruits might be replaced by green leafy vegetables the by sweet potatoes as the seasons progress). You can see if this is the typical case by using semi-quantitative methods (e.g. crop calendars, food calendars, market data). This will give some context if you see differences. You could use some form of hunger scale or food availability score but these may also be subject to seasonality. I hope this is of some use.