Listen up, people.
Flare is not the same as flair, so don’t use one when you mean the other.
A flare is a sudden burst of flame or light:
A solar flare will cause the aurora borealis to be visible (except for wherever I happen to be at the time, which will be clouded over.)
Or it’s something that starts out narrow and ends up wide:
The sleeve of the gown was a graceful flare, trimmed with gold embroidery at the open end.
A flair is a knack for doing something stylishly and/or particularly well:
Janet has a flair for mathematical puzzles.
Flair without the definite or indefinite article refers to a quality of stylishness, élan, and panache:
The final entry in the show was presented with even more flair than the ones that preceded it.
Highway flares, of course, are related to the first definition, since they spring into light with a sudden burst when struck. (They also give us the technical term flare out – as in, the first EMT to respond to the accident flared out the scene, meaning that they lit flares and placed them on the roadway to warn drivers of the obstruction. I love technical jargon and specialized lingo; they do fascinating things to the language.)