Dazzling or stunning.
Literally. It’s from the French word for “to strike by lightning”.
The crepuscular evening gray was shattered by a foudroyant thunderstorm.
TMI moment: The etymology reminded me of the word fulgent – shining brightly, radiant. So I looked that up too. My old American Heritage lists the origin of foudroyant as “fulgere, to flash” and the origin of fulgent as “fulgere, to shine”. Where are their copyeditors?!