heat lightning

noun3

1. •
   Lightning and/or thunder which the observer attributes to heat rather than a storm (e.g. because the storm/rain is too distant to be seen, or because there is no rain, as with dry lightning).

   • The beginning of a watery diarrheal event is said to be marked by a great deal of noise, characterized as […] rumbling (tzilelet 'rumbling sound of heat lightning in the rainy season'), […] — 2015
2. •
   Visible lightning that occurs too far away for the resulting thunder to be audible by the observer.
3. •
   Thunder that is heard without lightning being seen by the observer; heat thunder.

   • THE RAIN FINALLY CAME FROM THE DARK GREY SKIES, SOFT AND TEMPTING AT FIRST, WITH THE SOUND OF HEAT LIGHTNING HOVERING OVER THE SKYSCRAPERS! [image is of a city being rained on, no lightning visible] — 2019