Dark clouds have covered the sky. Sameer says it will definitely rain, since dark clouds always…

Why

Samir's rule comes from real experience — dark, heavy clouds genuinely are one of the strongest everyday signs that rain is likely, and reading the sky that way has probably served him well many times. The gap is 'likely' quietly becoming 'certain'. Rain depends on more than just clouds looking dark: the wind can carry those same clouds away before they release their water, the air below might be too dry for the falling drops to reach the ground without evaporating first, or the clouds may simply not yet hold enough moisture to actually fall. Weather forecasters use several instruments together — pressure readings from a barometer, humidity from a hygrometer, wind direction — precisely because no single sign, including dark clouds, guarantees an outcome by itself. Test: notice how often a dark, threatening sky in real life passes by with barely a drop, or arrives an hour later than expected, or not at all — proof that clouds alone aren't a certainty. His mother is right: dark clouds make rain likely, not certain, which is exactly why forecasting uses many instruments together rather than trusting one visual sign.