"A colloquial expression used in the south and midwest North America referring to a cold snap that occurs in late spring when the blackberries are in bloom," Wikipedia says.
That's not the way I remember it. Late-spring cold was dogwood winter. Mid-summer cold was blackberry winter. The time when blackberries were in fruit — not in flower.
Doesn't matter. Both are lovely ways to talk about unseasonable chill. Poetic descriptions of essential contradictions.
And the blackberries are in fruit and ready for picking. I see them along side roads and fence rows, in what remains of the meadow. They should peak this weekend.
(Photo: Wikipedia)