The first time we saw one of those notices, we thought someone had got the seasons seriously wrong. But they can be seen at several food markets.
But who says spring has to happen around april? The chinese new year (year of the monkey) will begin on feb 8 2016. And the first day of a new year is already considered spring. Cleaning everything in october leaves ample time to prepare for the festivities. So these notices announce cleaning activities to prepare for spring.