Literal translation
It's a heat that knocks you out.
Meaning
it's a dazing, heavy heat
Explanation
This expression describes overwhelming heat through its effect on the mind: ensucant, the present participle of the verb ensuca, to stun or to knock out, pictures the heat as a blow to the head, capable of momentarily dazing whoever is exposed to it. The word ensuca shares its root with suc, the head, which reinforces the idea of a localised shock to the skull, well beyond a diffuse feeling of discomfort. The expression thus captures a phenomenon well known in Provençal summers, that of a heat so intense it numbs thought, slows movement, and produces a sense of dizziness or stupor. It belongs to a family of weather expressions that personify extremes of temperature through an aggressive physical action, a family that also includes fai un fre de loup and fai fre que pelo for cold. It is said in ordinary register, typically in the height of summer, to comment on heat judged barely bearable.