The 12-year-old boy was standing under a pouring roof drainpipe, using the umbrella to shield his body, in his garden in Posadas, Argentina.
Video footage shows a powerful bolt of lightning lance down from the almost clear sky and strike right by him.
Carolina Koturm, who was filming her son, shrieks and drops her phone as her garden fence bursts into flames .
She told local media: "It was morning, I was with my daughter in the room calming her, because she is scared of lightning.
"Then the lady who works in my house told me that my son was walking in the rain and I started filming because I was making a joke, and right next to him the lightning struck.
"Thank God, nothing happened to him."
The fierce electrical storm reportedly had wide-ranging effects in the region on Saturday.
In San Pedro del Parana, 68 miles from the unnamed 12-year-old's lucky escape, two brothers were not so fortunate during a lightning strike.
Sinforiano Venialgo Vazquez, 43, and Simon Venialgo Vazquez, 41, were killed when lightning struck their home.
The cause of death in both cases was electrocution though no more details were available.
There were also reports of animals killed by lightning in the Santa Rosa area, on the Argentine side of the Parana River.