Scorching heat affects people's body - not only their skin.
The word "سحنة" refers to the physical constitution or bodily strength of an individual. The adjective "الصغيفة" means "frail" or "feeble," indicating a lack of physical robustness or endurance.

It can be translated as "The scorching heat burned my frail physique" or "The intense heat seared my feeble body." It suggests that the speaker's physical weakness made them more susceptible to the adverse effects of the hot weather.