This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Most biomes in this atlas carry both a temperature ceiling and a temperature floor: the desert's heat, the tundra's cold, the temperate forest's comfortable middle. The mangrove forest does not fit that pattern cleanly, and being honest about that gap is more useful than forcing a number that does not exist. Research for this entry found a well established cold tolerance threshold: the University of Florida's own habitat requirements page for South Florida puts survival at temperatures above 19C, and states plainly that mangroves cannot tolerate a swing of more than about 10C in a short period, or any freeze at all, however brief. That single number, not a heat ceiling, is what actually draws the biome's boundary around the world, which is why mangroves stop appearing as the coastline bends away from the tropics into any latitude that sees frost.
What the research did not find was an equally honest heat ceiling or a single global rainfall figure, and this entry does not invent one. Mangroves are, if anything, remarkably heat tolerant compared to most trees, since the tropical and subtropical coasts they occupy stay warm year round; heat is simply not the constraint doing the work. Rainfall is even less uniform: a peer reviewed survey of Colombian mangrove forests found them thriving on under 500mm of rain a year on the arid Guajira Peninsula coast and on more than 7000mm a year in the super humid forests of the Pacific coast, a fourteenfold range within a single country that makes any single annual precipitation figure for the biome actively misleading rather than merely imprecise.
This is the same discipline the atlas already applies to a population figure nobody can honestly state: better an accurate half of the picture, with the gap named, than a complete looking number quietly built on nothing.