Could you say 'The gale was blowing about his jacket' ? I'd like to express the repetitive movement of his jacket going from side to side.
Whipping could be used metaphorically, to describe both the wind and the jacket:
2.0 Move fast or suddenly in a specified direction:
In the continuous form, the word picture of "quick motion" is ongoing, evoking the image of a literal whip being drawn back and struck forward repetitively.
It applies to the jacket metaphorically as it moves back and forth, and applies to the wind as the cause of the jackets whipping motion.
I'd go with His coat was flapping in the wind.
1. the action of striking someone or something repeatedly and violently. see google.com, “buffeting” Link
• "His nylon jacket was repeatedly buffeted by the howling gale"
Buffet verb: 1. (especially of wind or waves) strike repeatedly and violently; batter. Synonyms: batter, pound, lash, strike, hit; see google.com, “buffet” Link
• "rough ocean winds buffeted their jackets"
Maybe battered? "The wind battered at his jacket". I assume he's wearing the jacket, not that it's hoisted into the air from the ground or a clothesline.
His jacket fluttered in the fierce gale.
How about these?
His jacket was fluttering as a gust of wind blew past us.
His jacket flapped about as a gust of wind blew past.
flap is defined as : a movement of a wing or an arm from side to side or up and down. But I suppose it could be used for describing the jacket's motion here.
Hi jacket beat against him as a gust of wind blew past.