Thunder over rain, not a louder rain
Storm is the one people request after rain. A second rain file would have been a waste. This loop is distant thunder over rain (CC0, Freesound, fattirewhitey) so the low end is actually different — rain.mp3 does not have that rumble. Close thunder that shakes the speakers was rejected; it reads as an explosion every four minutes and destroys a reading block.
Use storm when you want weather with weight. If a rumble still startles you, go back to rain. If you wanted wind without water, use wind. Do not run storm and rain together: they fight, and you get a fake downpour that never existed in either recording.
The in-room Storm control is this MP3. This page is the same bytes with a play button, for people who searched for thunder study sounds and did not want to create a room first. CC0, no required credit, recordist named anyway.
Open a study room and keep Storm on your side only.