Underwater is a normal environmental condition ... extruded materials absorb water vapor, not release it ...
It's believed Krakatoa's November 1883 eruption was a steam event ... sea water flowing into the magma chamber reached a critical mass and flash into water vapor ... that vapor quickly condensed back into liquid as temperatures fell ... within a few minutes and within a few miles ... like the recent Tonga eruption ... and here I'm including sulfuric acid with "water" ... most eruptions have some sulfur ...
Tonga was about equal to the most powerful of nuclear weapons ... and it takes about 20 minutes for a major hurricane to completely erase all traces of such weapon ... meaning volcanoes don't affect weather ... but weather effects volcanoes ... and I'm guessing there's more water in a Nebraska thunderstorm than in an average volcano ...