The first clue is the date, which is mm—dd-yyyy, only really used in the US.
Also, while not “from glancing”, the article speaks in the context of heat in US cities.
But yes, the author is likely taking for granted that non-US residents would read the article.
Why should they need to? Should French journalists account for French-speaking Americans? What about German, Nigerian and Chinese ones?
The only reason this argument ever comes up is because English is the most common second-language spoken. American, British, Aussie, etc journalists have no more moral or reasonable responsibility to account for non-native/foreign audiences than any other nationalities do.
If you want to read a foreign publication, it's on you to deal with their local norms.
They don't have to: French, Germans, Nigerians, and Chinese all use Celsius.
>The only reason this argument ever comes up is because English is the most common second-language spoken.
No, it only comes up because Americans are the only people who use Fahrenheit.