When did "thunderstorm" replace "tempest" in common English usage?
I ask the question because my great-great grandmother, who lived in South Weymouth, Massachusetts, used the term frequently in her dairy of the year 1905.
The OED dates the first use of "thunder-storm" to around 1656, with the first cite for "thunderstorm" without the hyphen coming from Charles Darwin's 1839 Voyage of the Beagle. A Google Ngram shows usage of tempest undergoing a century-long downward slide before being eclipsed for good by thunderstorm in the late 1970s.
However, bear in mind that the word tempest is often (I would guess predominantly) used metaphorically in the modern era, whereas with thunderstorm the literal definition is pretty much all you get. The Tempest is also the title of a well-known Shakespeare play, which presumably inflates its usage quite a bit. So I would guess that the original use of tempest was probably supplanted by thunderstorm many decades before the 1970s.
One thing to note about a thunderstorm is that it specifically implies thunder - as the word is in the name itself. Whereas heavy wind and rain could be considered a tempest without thunder of any kind.
Though "tempest" is not very commonly used in casual conversation. "Storm" would be acceptable, and does not specifically denote the presence of thunder.