Looking at a map, Ved says city X is closer to the equator than city Y, so X must be hotter than Y

Why

Ved has spotted a real and strong pattern — distance from the equator IS the single biggest reason some places are hotter than others, because near the equator the Sun's rays hit more directly all year. The mistake is turning a strong pattern into a rule with no exceptions. Height above sea level matters a lot too: the air gets colder the higher you go, so a city high up in the mountains near the equator can stay cool and spring-like all year, cooler than a low-lying city much farther from the equator in its summer. Being near the sea versus deep inland changes things as well. Test it: some cities sit almost exactly on the equator yet have mild, jacket-in-the-evening weather year-round, because they are two or three kilometres up in the mountains. His sister is right: closer to the equator makes a place hotter far more often than not, but altitude and other factors can override it — a strong pattern is not the same as a rule without exceptions.