This is a news article about a journalist using a more intensive adjective to describe an intensified phenomenon. The original Reuters article would probably have been more compelling reading.
The article has nothing to do with the literal specific meaning of one word and everything to do with how people consume and relate to climate change messaging. That's not "words", and it actually requires a good deal more thinking.
- Left: Words are words
- Middle: Only a profoundly ignorant person would say [that]
- Right: Words are words
We could still use "heatwave" with a magnitude suffix, like hurricanes. It's likely "heat storms" will need the magnitude suffix anyway.