Levels of production mean nothing when we're talking about whether not or there's a 25% surplus. Before this, only three realms had a 25% or higher surplus in the last three months - all small realms, making up just 20% of the continent combined. Every other realm had well under 25% surplus, according to the stats. If 80% of the island had well under 25%, chances are the whole island had an average of under 25%. We needed an increase in food to get to that, not a drop. But every realm did drop - aside from Kindara, of course, who managed to get away with the by far smallest drop in surplus and the by far largest increase in gold.
Given that we needed an increase in food to get a 25% surplus, it seems unlikely that weather alone has turned our needed increase into a huge drop.