Everywhere on earth, including equatorial regions, has hail. Hail is frozen water, or ice. In fact, the highest incidence of hail in the world is in the region of Kericho in Kenya, which had 132 days of hail one year, and averages 50 days/year of hail. Kericho is within 50 miles of the equator.

Lots of places in equatorial Africa and Asia have high mountains, where it snows at least seasonally, and in some places there is permanent snow cover at higher elevations.

At lower elevations, people often brought in ice from higher elevations. In Mughal India (and probably earlier) there were "barafkhanas" (literally ice houses) where ice was brought in from mountains as far away as Kashmir (500 miles from Delhi), and stored in underground cellars packed in straw. It was sold for cooling sherbets (drinks), while the rich also used it for cold baths. When the British arrived, they would bring ice on cargo ships, because it turned out it was cheaper to haul in a boatful of ice from Boston to Calcutta than to transport overland from the Himalayas. Boston was big in the ice business, because of the ready availability of winter ice from lots of ponds and lakes, plus plenty of sawdust to pack it in from the lumber milss. The ice-exporting industry reached its peak in the late 19th century, and the primary destinations were India and Brazil.

In deserts, it often gets cool/dry enough at nights to create ice in specialized structures built for ice making. Typically, the ice chamber is a hole dug into the ground to store the water, which is covered with a thick-walled conical building made of sand and clay. Evaporative cooling keeps the temperature low (much the same principle as desert coolers, but on the scale of the building itself). They were common in Persia, where they were known as "yakhachais", but they have been built in many tropical deserts where the climate is too hot for ice and not enough rainfall for hail. They get cold enough that in the morning, you'll see a layer of ice floating on the water pit.

Of course, that doesn't cover every individual living in the tropics. There were plenty of places that were too warm for natural ice and sufficiently poor and/or isolated for the ice trade networks. But in many places, people would have a familiarity with the concept even if they saw it rarely.