Actually, the color/season listings in the RCI Resort Directory do not correspond to the Wyndham grid season values. For instance, in the Resort Directory the WDW DVCs are listed as Red year-round, but in terms of Wyndham points via the portal much of the year is High (not Prime) and even some Value season. The best way to tell is by searching via the Wyndham/RCI portal, but that assumes that there is an available unit at the resort you want for the week you want. For DVC (my only area of direct experience, can you tell?) all of Orlando shares a season, so even if there wasn't any DVC available I could tell the season by searching another Orlando resort for the week I wanted. I assume you could do this in other regions where resorts are geographically close, but I haven't tried.
And of course, since it's RCI, they could change the season at any time.